src/testdir/test_functions.vim

" Tests for various functions.

source shared.vim
source check.vim
source term_util.vim
source screendump.vim
import './vim9.vim' as v9

" Must be done first, since the alternate buffer must be unset.
func Test_00_bufexists()
  call assert_equal(0, bufexists('does_not_exist'))
  call assert_equal(1, bufexists(bufnr('%')))
  call assert_equal(0, bufexists(0))
  new Xfoo
  let bn = bufnr('%')
  call assert_equal(1, bufexists(bn))
  call assert_equal(1, bufexists('Xfoo'))
  call assert_equal(1, bufexists(getcwd() . '/Xfoo'))
  call assert_equal(1, bufexists(0))
  bw
  call assert_equal(0, bufexists(bn))
  call assert_equal(0, bufexists('Xfoo'))
endfunc

func Test_has()
  call assert_equal(1, has('eval'))
  call assert_equal(1, has('eval', 1))

  if has('unix')
    call assert_equal(1, or(has('ttyin'), 1))
    call assert_equal(0, and(has('ttyout'), 0))
    call assert_equal(1, has('multi_byte_encoding'))
  endif
  call assert_equal(1, has('vcon', 1))
  call assert_equal(1, has('mouse_gpm_enabled', 1))

  call assert_equal(0, has('nonexistent'))
  call assert_equal(0, has('nonexistent', 1))

  " Will we ever have patch 9999?
  let ver = 'patch-' .. v:version / 100 .. '.' .. v:version % 100 .. '.9999'
  call assert_equal(0, has(ver))

  " There actually isn't a patch 9.0.0, but this is more consistent.
  call assert_equal(1, has('patch-9.0.0'))
endfunc

func Test_empty()
  call assert_equal(1, empty(''))
  call assert_equal(0, empty('a'))

  call assert_equal(1, empty(0))
  call assert_equal(1, empty(-0))
  call assert_equal(0, empty(1))
  call assert_equal(0, empty(-1))

  call assert_equal(1, empty(0.0))
  call assert_equal(1, empty(-0.0))
  call assert_equal(0, empty(1.0))
  call assert_equal(0, empty(-1.0))
  call assert_equal(0, empty(1.0/0.0))
  call assert_equal(0, empty(0.0/0.0))

  call assert_equal(1, empty([]))
  call assert_equal(0, empty(['a']))

  call assert_equal(1, empty({}))
  call assert_equal(0, empty({'a':1}))

  call assert_equal(1, empty(v:null))
  call assert_equal(1, empty(v:none))
  call assert_equal(1, empty(v:false))
  call assert_equal(0, empty(v:true))

  if has('channel')
    call assert_equal(1, empty(test_null_channel()))
  endif
  if has('job')
    call assert_equal(1, empty(test_null_job()))
  endif

  call assert_equal(0, empty(function('Test_empty')))
  call assert_equal(0, empty(function('Test_empty', [0])))

  call assert_fails("call empty(test_void())", ['E340:', 'E685:'])
  call assert_fails("call empty(test_unknown())", ['E340:', 'E685:'])
endfunc

func Test_test_void()
  call assert_fails('echo 1 == test_void()', 'E1031:')
  call assert_fails('echo 1.0 == test_void()', 'E1031:')
  call assert_fails('let x = json_encode(test_void())', ['E340:', 'E685:'])
  call assert_fails('let x = copy(test_void())', ['E340:', 'E685:'])
  call assert_fails('let x = copy([test_void()])', 'E1031:')
endfunc

func Test_islocked()
  call assert_fails('call islocked(99)', 'E475:')
  call assert_fails('call islocked("s: x")', 'E488:')
endfunc

func Test_len()
  call assert_equal(1, len(0))
  call assert_equal(2, len(12))

  call assert_equal(0, len(''))
  call assert_equal(2, len('ab'))

  call assert_equal(0, len([]))
  call assert_equal(0, len(test_null_list()))
  call assert_equal(2, len([2, 1]))

  call assert_equal(0, len({}))
  call assert_equal(0, len(test_null_dict()))
  call assert_equal(2, len({'a': 1, 'b': 2}))

  call assert_fails('call len(v:none)', 'E701:')
  call assert_fails('call len({-> 0})', 'E701:')
endfunc

func Test_max()
  call assert_equal(0, max([]))
  call assert_equal(2, max([2]))
  call assert_equal(2, max([1, 2]))
  call assert_equal(2, max([1, 2, v:null]))

  call assert_equal(0, max({}))
  call assert_equal(2, max({'a':1, 'b':2}))

  call assert_fails('call max(1)', 'E712:')
  call assert_fails('call max(v:none)', 'E712:')

  " check we only get one error
  call assert_fails('call max([#{}, [1]])', ['E728:', 'E728:'])
  call assert_fails('call max(#{a: {}, b: [1]})', ['E728:', 'E728:'])
endfunc

func Test_min()
  call assert_equal(0, min([]))
  call assert_equal(2, min([2]))
  call assert_equal(1, min([1, 2]))
  call assert_equal(0, min([1, 2, v:null]))

  call assert_equal(0, min({}))
  call assert_equal(1, min({'a':1, 'b':2}))

  call assert_fails('call min(1)', 'E712:')
  call assert_fails('call min(v:none)', 'E712:')
  call assert_fails('call min([1, {}])', 'E728:')

  " check we only get one error
  call assert_fails('call min([[1], #{}])', ['E745:', 'E745:'])
  call assert_fails('call min(#{a: [1], b: #{}})', ['E745:', 'E745:'])
endfunc

func Test_strwidth()
  for aw in ['single', 'double']
    exe 'set ambiwidth=' . aw
    call assert_equal(0, strwidth(''))
    call assert_equal(1, strwidth("\t"))
    call assert_equal(3, strwidth('Vim'))
    call assert_equal(4, strwidth(1234))
    call assert_equal(5, strwidth(-1234))

    call assert_equal(2, strwidth('😉'))
    call assert_equal(17, strwidth('Eĥoŝanĝo ĉiuĵaŭde'))
    call assert_equal((aw == 'single') ? 6 : 7, strwidth('Straße'))

    call assert_fails('call strwidth({->0})', 'E729:')
    call assert_fails('call strwidth([])', 'E730:')
    call assert_fails('call strwidth({})', 'E731:')
  endfor

  call assert_equal(3, strwidth(1.2))
  call v9.CheckDefAndScriptFailure(['echo strwidth(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])

  set ambiwidth&
endfunc

func Test_str2nr()
  call assert_equal(0, str2nr(''))
  call assert_equal(1, str2nr('1'))
  call assert_equal(1, str2nr(' 1 '))

  call assert_equal(1, str2nr('+1'))
  call assert_equal(1, str2nr('+ 1'))
  call assert_equal(1, str2nr(' + 1 '))

  call assert_equal(-1, str2nr('-1'))
  call assert_equal(-1, str2nr('- 1'))
  call assert_equal(-1, str2nr(' - 1 '))

  call assert_equal(123456789, str2nr('123456789'))
  call assert_equal(-123456789, str2nr('-123456789'))

  call assert_equal(5, str2nr('101', 2))
  call assert_equal(5, '0b101'->str2nr(2))
  call assert_equal(5, str2nr('0B101', 2))
  call assert_equal(-5, str2nr('-101', 2))
  call assert_equal(-5, str2nr('-0b101', 2))
  call assert_equal(-5, str2nr('-0B101', 2))

  call assert_equal(65, str2nr('101', 8))
  call assert_equal(65, str2nr('0101', 8))
  call assert_equal(-65, str2nr('-101', 8))
  call assert_equal(-65, str2nr('-0101', 8))
  call assert_equal(65, str2nr('0o101', 8))
  call assert_equal(65, str2nr('0O0101', 8))
  call assert_equal(-65, str2nr('-0O101', 8))
  call assert_equal(-65, str2nr('-0o0101', 8))

  call assert_equal(11259375, str2nr('abcdef', 16))
  call assert_equal(11259375, str2nr('ABCDEF', 16))
  call assert_equal(-11259375, str2nr('-ABCDEF', 16))
  call assert_equal(11259375, str2nr('0xabcdef', 16))
  call assert_equal(11259375, str2nr('0Xabcdef', 16))
  call assert_equal(11259375, str2nr('0XABCDEF', 16))
  call assert_equal(-11259375, str2nr('-0xABCDEF', 16))

  call assert_equal(1, str2nr("1'000'000", 10, 0))
  call assert_equal(256, str2nr("1'0000'0000", 2, 1))
  call assert_equal(262144, str2nr("1'000'000", 8, 1))
  call assert_equal(1000000, str2nr("1'000'000", 10, 1))
  call assert_equal(1000, str2nr("1'000''000", 10, 1))
  call assert_equal(65536, str2nr("1'00'00", 16, 1))

  call assert_equal(0, str2nr('0x10'))
  call assert_equal(0, str2nr('0b10'))
  call assert_equal(0, str2nr('0o10'))
  call assert_equal(1, str2nr('12', 2))
  call assert_equal(1, str2nr('18', 8))
  call assert_equal(1, str2nr('1g', 16))

  call assert_equal(0, str2nr(v:null))
  call assert_equal(0, str2nr(v:none))

  call assert_fails('call str2nr([])', 'E730:')
  call assert_fails('call str2nr({->2})', 'E729:')
  call assert_equal(1, str2nr(1.2))
  call v9.CheckDefAndScriptFailure(['echo str2nr(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
  call assert_fails('call str2nr(10, [])', 'E745:')
endfunc

func Test_strftime()
  CheckFunction strftime

  " Format of strftime() depends on system. We assume
  " that basic formats tested here are available and
  " identical on all systems which support strftime().
  "
  " The 2nd parameter of strftime() is a local time, so the output day
  " of strftime() can be 17 or 18, depending on timezone.
  call assert_match('^2017-01-1[78]$', strftime('%Y-%m-%d', 1484695512))
  "
  call assert_match('^\d\d\d\d-\(0\d\|1[012]\)-\([012]\d\|3[01]\) \([01]\d\|2[0-3]\):[0-5]\d:\([0-5]\d\|60\)$', '%Y-%m-%d %H:%M:%S'->strftime())

  call assert_fails('call strftime([])', 'E730:')
  call assert_fails('call strftime("%Y", [])', 'E745:')

  " Check that the time changes after we change the timezone
  " Save previous timezone value, if any
  if exists('$TZ')
    let tz = $TZ
  endif

  " Force EST and then UTC, save the current hour (24-hour clock) for each
  let $TZ = 'EST' | let est = strftime('%H')
  let $TZ = 'UTC' | let utc = strftime('%H')

  " Those hours should be two bytes long, and should not be the same; if they
  " are, a tzset(3) call may have failed somewhere
  call assert_equal(strlen(est), 2)
  call assert_equal(strlen(utc), 2)
  " TODO: this fails on MS-Windows
  if has('unix')
    call assert_notequal(est, utc)
  endif

  " If we cached a timezone value, put it back, otherwise clear it
  if exists('tz')
    let $TZ = tz
  else
    unlet $TZ
  endif
endfunc

func Test_strptime()
  CheckFunction strptime

  if exists('$TZ')
    let tz = $TZ
  endif
  let $TZ = 'UTC'

  call assert_equal(1484653763, strptime('%Y-%m-%d %T', '2017-01-17 11:49:23'))

  " Force DST and check that it's considered
  let $TZ = 'WINTER0SUMMER,J1,J365'
  call assert_equal(1484653763 - 3600, strptime('%Y-%m-%d %T', '2017-01-17 11:49:23'))

  call assert_fails('call strptime()', 'E119:')
  call assert_fails('call strptime("xxx")', 'E119:')
  call assert_equal(0, strptime("%Y", ''))
  call assert_equal(0, strptime("%Y", "xxx"))

  if exists('tz')
    let $TZ = tz
  else
    unlet $TZ
  endif
endfunc

func Test_resolve_unix()
  CheckUnix

  " Xlink1 -> Xlink2
  " Xlink2 -> Xlink3
  silent !ln -s -f Xlink2 Xlink1
  silent !ln -s -f Xlink3 Xlink2
  call assert_equal('Xlink3', resolve('Xlink1'))
  call assert_equal('./Xlink3', resolve('./Xlink1'))
  call assert_equal('Xlink3/', resolve('Xlink2/'))
  " FIXME: these tests result in things like "Xlink2/" instead of "Xlink3/"?!
  "call assert_equal('Xlink3/', resolve('Xlink1/'))
  "call assert_equal('./Xlink3/', resolve('./Xlink1/'))
  "call assert_equal(getcwd() . '/Xlink3/', resolve(getcwd() . '/Xlink1/'))
  call assert_equal(getcwd() . '/Xlink3', resolve(getcwd() . '/Xlink1'))

  " Test resolve() with a symlink cycle.
  " Xlink1 -> Xlink2
  " Xlink2 -> Xlink3
  " Xlink3 -> Xlink1
  silent !ln -s -f Xlink1 Xlink3
  call assert_fails('call resolve("Xlink1")',   'E655:')
  call assert_fails('call resolve("./Xlink1")', 'E655:')
  call assert_fails('call resolve("Xlink2")',   'E655:')
  call assert_fails('call resolve("Xlink3")',   'E655:')
  call delete('Xlink1')
  call delete('Xlink2')
  call delete('Xlink3')

  silent !ln -s -f Xresolvedir//Xfile Xresolvelink
  call assert_equal('Xresolvedir/Xfile', resolve('Xresolvelink'))
  call delete('Xresolvelink')

  silent !ln -s -f Xlink2/ Xlink1
  call assert_equal('Xlink2', 'Xlink1'->resolve())
  call assert_equal('Xlink2/', resolve('Xlink1/'))
  call delete('Xlink1')

  silent !ln -s -f ./Xlink2 Xlink1
  call assert_equal('Xlink2', resolve('Xlink1'))
  call assert_equal('./Xlink2', resolve('./Xlink1'))
  call delete('Xlink1')

  call assert_equal('/', resolve('/'))
endfunc

func s:normalize_fname(fname)
  let ret = substitute(a:fname, '\', '/', 'g')
  let ret = substitute(ret, '//', '/', 'g')
  return ret->tolower()
endfunc

func Test_resolve_win32()
  CheckMSWindows

  " test for shortcut file
  if executable('cscript')
    new Xresfile
    wq
    let lines =<< trim END
	Set fs = CreateObject("Scripting.FileSystemObject")
	Set ws = WScript.CreateObject("WScript.Shell")
	Set shortcut = ws.CreateShortcut("Xlink.lnk")
	shortcut.TargetPath = fs.BuildPath(ws.CurrentDirectory, "Xresfile")
	shortcut.Save
    END
    call writefile(lines, 'link.vbs')
    silent !cscript link.vbs
    call delete('link.vbs')
    call assert_equal(s:normalize_fname(getcwd() . '\Xresfile'), s:normalize_fname(resolve('./Xlink.lnk')))
    call delete('Xresfile')

    call assert_equal(s:normalize_fname(getcwd() . '\Xresfile'), s:normalize_fname(resolve('./Xlink.lnk')))
    call delete('Xlink.lnk')
  else
    echomsg 'skipped test for shortcut file'
  endif

  " remove files
  call delete('Xlink')
  call delete('Xdir', 'd')
  call delete('Xresfile')

  " test for symbolic link to a file
  new Xresfile
  wq
  call assert_equal('Xresfile', resolve('Xresfile'))
  silent !mklink Xlink Xresfile
  if !v:shell_error
    call assert_equal(s:normalize_fname(getcwd() . '\Xresfile'), s:normalize_fname(resolve('./Xlink')))
    call delete('Xlink')
  else
    echomsg 'skipped test for symbolic link to a file'
  endif
  call delete('Xresfile')

  " test for junction to a directory
  call mkdir('Xdir')
  silent !mklink /J Xlink Xdir
  if !v:shell_error
    call assert_equal(s:normalize_fname(getcwd() . '\Xdir'), s:normalize_fname(resolve(getcwd() . '/Xlink')))

    call delete('Xdir', 'd')

    " test for junction already removed
    call assert_equal(s:normalize_fname(getcwd() . '\Xlink'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
    call delete('Xlink')
  else
    echomsg 'skipped test for junction to a directory'
    call delete('Xdir', 'd')
  endif

  " test for symbolic link to a directory
  call mkdir('Xdir')
  silent !mklink /D Xlink Xdir
  if !v:shell_error
    call assert_equal(s:normalize_fname(getcwd() . '\Xdir'), s:normalize_fname(resolve(getcwd() . '/Xlink')))

    call delete('Xdir', 'd')

    " test for symbolic link already removed
    call assert_equal(s:normalize_fname(getcwd() . '\Xlink'), s:normalize_fname(resolve(getcwd() . '/Xlink')))
    call delete('Xlink')
  else
    echomsg 'skipped test for symbolic link to a directory'
    call delete('Xdir', 'd')
  endif

  " test for buffer name
  new Xbuffile
  wq
  silent !mklink Xlink Xbuffile
  if !v:shell_error
    edit Xlink
    call assert_equal('Xlink', bufname('%'))
    call delete('Xlink')
    bw!
  else
    echomsg 'skipped test for buffer name'
  endif
  call delete('Xbuffile')

  " test for reparse point
  call mkdir('Xdir')
  call assert_equal('Xdir', resolve('Xdir'))
  silent !mklink /D Xdirlink Xdir
  if !v:shell_error
    w Xdir/text.txt
    call assert_equal('Xdir/text.txt', resolve('Xdir/text.txt'))
    call assert_equal(s:normalize_fname(getcwd() . '\Xdir\text.txt'), s:normalize_fname(resolve('Xdirlink\text.txt')))
    call assert_equal(s:normalize_fname(getcwd() . '\Xdir'), s:normalize_fname(resolve('Xdirlink')))
    call delete('Xdirlink')
  else
    echomsg 'skipped test for reparse point'
  endif

  call delete('Xdir', 'rf')
endfunc

func Test_simplify()
  call assert_equal('',            simplify(''))
  call assert_equal('/',           simplify('/'))
  call assert_equal('/',           simplify('/.'))
  call assert_equal('/',           simplify('/..'))
  call assert_equal('/...',        simplify('/...'))
  call assert_equal('//path',      simplify('//path'))
  if has('unix')
    call assert_equal('/path',       simplify('///path'))
    call assert_equal('/path',       simplify('////path'))
  endif

  call assert_equal('./dir/file',  './dir/file'->simplify())
  call assert_equal('./dir/file',  simplify('.///dir//file'))
  call assert_equal('./dir/file',  simplify('./dir/./file'))
  call assert_equal('./file',      simplify('./dir/../file'))
  call assert_equal('../dir/file', simplify('dir/../../dir/file'))
  call assert_equal('./file',      simplify('dir/.././file'))
  call assert_equal('../dir',      simplify('./../dir'))
  call assert_equal('..',          simplify('../testdir/..'))
  call mkdir('Xsimpdir')
  call assert_equal('.',           simplify('Xsimpdir/../.'))
  call delete('Xsimpdir', 'd')

  call assert_fails('call simplify({->0})', 'E729:')
  call assert_fails('call simplify([])', 'E730:')
  call assert_fails('call simplify({})', 'E731:')
  call assert_equal('1.2', simplify(1.2))
  call v9.CheckDefAndScriptFailure(['echo simplify(1.2)'], ['E1013: Argument 1: type mismatch, expected string but got float', 'E1174: String required for argument 1'])
endfunc

func Test_pathshorten()
  call assert_equal('', pathshorten(''))
  call assert_equal('foo', pathshorten('foo'))
  call assert_equal('/foo', '/foo'->pathshorten())
  call assert_equal('f/', pathshorten('foo/'))
  call assert_equal('f/bar', pathshorten('foo/bar'))
  call assert_equal('f/b/foobar', 'foo/bar/foobar'->pathshorten())
  call assert_equal('/f/b/foobar', pathshorten('/foo/bar/foobar'))
  call assert_equal('.f/bar', pathshorten('.foo/bar'))
  call assert_equal('~f/bar', pathshorten('~foo/bar'))
  call assert_equal('~.f/bar', pathshorten('~.foo/bar'))
  call assert_equal('.~f/bar', pathshorten('.~foo/bar'))
  call assert_equal('~/f/bar', pathshorten('~/foo/bar'))
  call assert_fails('call pathshorten([])', 'E730:')

  " test pathshorten with optional variable to set preferred size of shortening
  call assert_equal('', pathshorten('', 2))
  call assert_equal('foo', pathshorten('foo', 2))
  call assert_equal('/foo', pathshorten('/foo', 2))
  call assert_equal('fo/', pathshorten('foo/', 2))
  call assert_equal('fo/bar', pathshorten('foo/bar', 2))
  call assert_equal('fo/ba/foobar', pathshorten('foo/bar/foobar', 2))
  call assert_equal('/fo/ba/foobar', pathshorten('/foo/bar/foobar', 2))
  call assert_equal('.fo/bar', pathshorten('.foo/bar', 2))
  call assert_equal('~fo/bar', pathshorten('~foo/bar', 2))
  call assert_equal('~.fo/bar', pathshorten('~.foo/bar', 2))
  call assert_equal('.~fo/bar', pathshorten('.~foo/bar', 2))
  call assert_equal('~/fo/bar', pathshorten('~/foo/bar', 2))
  call assert_fails('call pathshorten([],2)', 'E730:')
  call assert_notequal('~/fo/bar', pathshorten('~/foo/bar', 3))
  call assert_equal('~/foo/bar', pathshorten('~/foo/bar', 3))
  call assert_equal('~/f/bar', pathshorten('~/foo/bar', 0))
endfunc

func Test_strpart()
  call assert_equal('de', strpart('abcdefg', 3, 2))
  call assert_equal('ab', strpart('abcdefg', -2, 4))
  call assert_equal('abcdefg', 'abcdefg'->strpart(-2))
  call assert_equal('fg', strpart('abcdefg', 5, 4))
  call assert_equal('defg', strpart('abcdefg', 3))
  call assert_equal('', strpart('abcdefg', 10))
  call assert_fails("let s=strpart('abcdef', [])", 'E745:')

  call assert_equal('lép', strpart('éléphant', 2, 4))
  call assert_equal('léphant', strpart('éléphant', 2))

  call assert_equal('é', strpart('éléphant', 0, 1, 1))
  call assert_equal('ép', strpart('éléphant', 3, 2, v:true))
  call assert_equal('ó', strpart('cómposed', 1, 1, 1))
endfunc

func Test_tolower()
  call assert_equal("", tolower(""))

  " Test with all printable ASCII characters.
  call assert_equal(' !"#$%&''()*+,-./0123456789:;<=>?@abcdefghijklmnopqrstuvwxyz[\]^_`abcdefghijklmnopqrstuvwxyz{|}~',
          \ tolower(' !"#$%&''()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'))

  " Test with a few uppercase diacritics.
  call assert_equal("aàáâãäåāăąǎǟǡả", tolower("AÀÁÂÃÄÅĀĂĄǍǞǠẢ"))
  call assert_equal("bḃḇ", tolower("BḂḆ"))
  call assert_equal("cçćĉċč", tolower("CÇĆĈĊČ"))
  call assert_equal("dďđḋḏḑ", tolower("DĎĐḊḎḐ"))
  call assert_equal("eèéêëēĕėęěẻẽ", tolower("EÈÉÊËĒĔĖĘĚẺẼ"))
  call assert_equal("fḟ ", tolower("FḞ "))
  call assert_equal("gĝğġģǥǧǵḡ", tolower("GĜĞĠĢǤǦǴḠ"))
  call assert_equal("hĥħḣḧḩ", tolower("HĤĦḢḦḨ"))
  call assert_equal("iìíîïĩīĭįiǐỉ", tolower("IÌÍÎÏĨĪĬĮİǏỈ"))
  call assert_equal("jĵ", tolower("JĴ"))
  call assert_equal("kķǩḱḵ", tolower("KĶǨḰḴ"))
  call assert_equal("lĺļľŀłḻ", tolower("LĹĻĽĿŁḺ"))
  call assert_equal("mḿṁ", tolower("MḾṀ"))
  call assert_equal("nñńņňṅṉ", tolower("NÑŃŅŇṄṈ"))
  call assert_equal("oòóôõöøōŏőơǒǫǭỏ", tolower("OÒÓÔÕÖØŌŎŐƠǑǪǬỎ"))
  call assert_equal("pṕṗ", tolower("PṔṖ"))
  call assert_equal("q", tolower("Q"))
  call assert_equal("rŕŗřṙṟ", tolower("RŔŖŘṘṞ"))
  call assert_equal("sśŝşšṡ", tolower("SŚŜŞŠṠ"))
  call assert_equal("tţťŧṫṯ", tolower("TŢŤŦṪṮ"))
  call assert_equal("uùúûüũūŭůűųưǔủ", tolower("UÙÚÛÜŨŪŬŮŰŲƯǓỦ"))
  call assert_equal("vṽ", tolower("VṼ"))
  call assert_equal("wŵẁẃẅẇ", tolower("WŴẀẂẄẆ"))
  call assert_equal("xẋẍ", tolower("XẊẌ"))
  call assert_equal("yýŷÿẏỳỷỹ", tolower("YÝŶŸẎỲỶỸ"))
  call assert_equal("zźżžƶẑẕ", tolower("ZŹŻŽƵẐẔ"))

  " Test with a few lowercase diacritics, which should remain unchanged.
  call assert_equal("aàáâãäåāăąǎǟǡả", tolower("aàáâãäåāăąǎǟǡả"))
  call assert_equal("bḃḇ", tolower("bḃḇ"))
  call assert_equal("cçćĉċč", tolower("cçćĉċč"))
  call assert_equal("dďđḋḏḑ", tolower("dďđḋḏḑ"))
  call assert_equal("eèéêëēĕėęěẻẽ", tolower("eèéêëēĕėęěẻẽ"))
  call assert_equal("fḟ", tolower("fḟ"))
  call assert_equal("gĝğġģǥǧǵḡ", tolower("gĝğġģǥǧǵḡ"))
  call assert_equal("hĥħḣḧḩẖ", tolower("hĥħḣḧḩẖ"))
  call assert_equal("iìíîïĩīĭįǐỉ", tolower("iìíîïĩīĭįǐỉ"))
  call assert_equal("jĵǰ", tolower("jĵǰ"))
  call assert_equal("kķǩḱḵ", tolower("kķǩḱḵ"))
  call assert_equal("lĺļľŀłḻ", tolower("lĺļľŀłḻ"))
  call assert_equal("mḿṁ ", tolower("mḿṁ "))
  call assert_equal("nñńņňʼnṅṉ", tolower("nñńņňʼnṅṉ"))
  call assert_equal("oòóôõöøōŏőơǒǫǭỏ", tolower("oòóôõöøōŏőơǒǫǭỏ"))
  call assert_equal("pṕṗ", tolower("pṕṗ"))
  call assert_equal("q", tolower("q"))
  call assert_equal("rŕŗřṙṟ", tolower("rŕŗřṙṟ"))
  call assert_equal("sśŝşšṡ", tolower("sśŝşšṡ"))
  call assert_equal("tţťŧṫṯẗ", tolower("tţťŧṫṯẗ"))
  call assert_equal("uùúûüũūŭůűųưǔủ", tolower("uùúûüũūŭůűųưǔủ"))
  call assert_equal("vṽ", tolower("vṽ"))
  call assert_equal("wŵẁẃẅẇẘ", tolower("wŵẁẃẅẇẘ"))
  call assert_equal("ẋẍ", tolower("ẋẍ"))
  call assert_equal("yýÿŷẏẙỳỷỹ", tolower("yýÿŷẏẙỳỷỹ"))
  call assert_equal("zźżžƶẑẕ", tolower("zźżžƶẑẕ"))

  " According to https://twitter.com/jifa/status/625776454479970304
  " Ⱥ (U+023A) and Ⱦ (U+023E) are the *only* code points to increase
  " in length (2 to 3 bytes) when lowercased. So let's test them.
  call assert_equal("ⱥ ⱦ", tolower("Ⱥ Ⱦ"))

  " This call to tolower with invalid utf8 sequence used to cause access to
  " invalid memory.
  call tolower("\xC0\x80\xC0")
  call tolower("123\xC0\x80\xC0")

  " Test in latin1 encoding
  let save_enc = &encoding
  set encoding=latin1
  call assert_equal("abc", tolower("ABC"))
  let &encoding = save_enc
endfunc

func Test_toupper()
  call assert_equal("", toupper(""))

  " Test with all printable ASCII characters.
  call assert_equal(' !"#$%&''()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`ABCDEFGHIJKLMNOPQRSTUVWXYZ{|}~',
          \ toupper(' !"#$%&''()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~'))

  " Test with a few lowercase diacritics.
  call assert_equal("AÀÁÂÃÄÅĀĂĄǍǞǠẢ", "aàáâãäåāăąǎǟǡả"->toupper())
  call assert_equal("BḂḆ", toupper("bḃḇ"))
  call assert_equal("CÇĆĈĊČ", toupper("cçćĉċč"))
  call assert_equal("DĎĐḊḎḐ", toupper("dďđḋḏḑ"))
  call assert_equal("EÈÉÊËĒĔĖĘĚẺẼ", toupper("eèéêëēĕėęěẻẽ"))
  call assert_equal("FḞ", toupper("fḟ"))
  call assert_equal("GĜĞĠĢǤǦǴḠ", toupper("gĝğġģǥǧǵḡ"))
  call assert_equal("HĤĦḢḦḨẖ", toupper("hĥħḣḧḩẖ"))
  call assert_equal("IÌÍÎÏĨĪĬĮǏỈ", toupper("iìíîïĩīĭįǐỉ"))
  call assert_equal("JĴǰ", toupper("jĵǰ"))
  call assert_equal("KĶǨḰḴ", toupper("kķǩḱḵ"))
  call assert_equal("LĹĻĽĿŁḺ", toupper("lĺļľŀłḻ"))
  call assert_equal("MḾṀ ", toupper("mḿṁ "))
  call assert_equal("NÑŃŅŇʼnṄṈ", toupper("nñńņňʼnṅṉ"))
  call assert_equal("OÒÓÔÕÖØŌŎŐƠǑǪǬỎ", toupper("oòóôõöøōŏőơǒǫǭỏ"))
  call assert_equal("PṔṖ", toupper("pṕṗ"))
  call assert_equal("Q", toupper("q"))
  call assert_equal("RŔŖŘṘṞ", toupper("rŕŗřṙṟ"))
  call assert_equal("SŚŜŞŠṠ", toupper("sśŝşšṡ"))
  call assert_equal("TŢŤŦṪṮẗ", toupper("tţťŧṫṯẗ"))
  call assert_equal("UÙÚÛÜŨŪŬŮŰŲƯǓỦ", toupper("uùúûüũūŭůűųưǔủ"))
  call assert_equal("VṼ", toupper("vṽ"))
  call assert_equal("WŴẀẂẄẆẘ", toupper("wŵẁẃẅẇẘ"))
  call assert_equal("ẊẌ", toupper("ẋẍ"))
  call assert_equal("YÝŸŶẎẙỲỶỸ", toupper("yýÿŷẏẙỳỷỹ"))
  call assert_equal("ZŹŻŽƵẐẔ", toupper("zźżžƶẑẕ"))

  " Test that uppercase diacritics, which should remain unchanged.
  call assert_equal("AÀÁÂÃÄÅĀĂĄǍǞǠẢ", toupper("AÀÁÂÃÄÅĀĂĄǍǞǠẢ"))
  call assert_equal("BḂḆ", toupper("BḂḆ"))
  call assert_equal("CÇĆĈĊČ", toupper("CÇĆĈĊČ"))
  call assert_equal("DĎĐḊḎḐ", toupper("DĎĐḊḎḐ"))
  call assert_equal("EÈÉÊËĒĔĖĘĚẺẼ", toupper("EÈÉÊËĒĔĖĘĚẺẼ"))
  call assert_equal("FḞ ", toupper("FḞ "))
  call assert_equal("GĜĞĠĢǤǦǴḠ", toupper("GĜĞĠĢǤǦǴḠ"))
  call assert_equal("HĤĦḢḦḨ", toupper("HĤĦḢḦḨ"))
  call assert_equal("IÌÍÎÏĨĪĬĮİǏỈ", toupper("IÌÍÎÏĨĪĬĮİǏỈ"))
  call assert_equal("JĴ", toupper("JĴ"))
  call assert_equal("KĶǨḰḴ", toupper("KĶǨḰḴ"))
  call assert_equal("LĹĻĽĿŁḺ", toupper("LĹĻĽĿŁḺ"))
  call assert_equal("MḾṀ", toupper("MḾṀ"))
  call assert_equal("NÑŃŅŇṄṈ", toupper("NÑŃŅŇṄṈ"))
  call assert_equal("OÒÓÔÕÖØŌŎŐƠǑǪǬỎ", toupper("OÒÓÔÕÖØŌŎŐƠǑǪǬỎ"))
  call assert_equal("PṔṖ", toupper("PṔṖ"))
  call assert_equal("Q", toupper("Q"))
  call assert_equal("RŔŖŘṘṞ", toupper("RŔŖŘṘṞ"))
  call assert_equal("SŚŜŞŠṠ", toupper("SŚŜŞŠṠ"))
  call assert_equal("TŢŤŦṪṮ", toupper("TŢŤŦṪṮ"))
  call assert_equal("UÙÚÛÜŨŪŬŮŰŲƯǓỦ", toupper("UÙÚÛÜŨŪŬŮŰŲƯǓỦ"))
  call assert_equal("VṼ", toupper("VṼ"))
  call assert_equal("WŴẀẂẄẆ", toupper("WŴẀẂẄẆ"))
  call assert_equal("XẊẌ", toupper("XẊẌ"))
  call assert_equal("YÝŶŸẎỲỶỸ", toupper("YÝŶŸẎỲỶỸ"))
  call assert_equal("ZŹŻŽƵẐẔ", toupper("ZŹŻŽƵẐẔ"))

  call assert_equal("Ⱥ Ⱦ", toupper("ⱥ ⱦ"))

  " This call to toupper with invalid utf8 sequence used to cause access to
  " invalid memory.
  call toupper("\xC0\x80\xC0")
  call toupper("123\xC0\x80\xC0")

  " Test in latin1 encoding
  let save_enc = &encoding
  set encoding=latin1
  call assert_equal("ABC", toupper("abc"))
  let &encoding = save_enc
endfunc

func Test_tr()
  call assert_equal('foo', tr('bar', 'bar', 'foo'))
  call assert_equal('zxy', 'cab'->tr('abc', 'xyz'))
  call assert_fails("let s=tr([], 'abc', 'def')", 'E730:')
  call assert_fails("let s=tr('abc', [], 'def')", 'E730:')
  call assert_fails("let s=tr('abc', 'abc', [])", 'E730:')
  call assert_fails("let s=tr('abcd', 'abcd', 'def')", 'E475:')
  set encoding=latin1
  call assert_fails("let s=tr('abcd', 'abcd', 'def')", 'E475:')
  call assert_equal('hEllO', tr('hello', 'eo', 'EO'))
  call assert_equal('hello', tr('hello', 'xy', 'ab'))
  call assert_fails('call tr("abc", "123", "₁₂")', 'E475:')
  set encoding=utf8
endfunc

" Tests for the mode() function
let current_modes = ''
func Save_mode()
  let g:current_modes = mode(0) . '-' . mode(1)
  return ''
endfunc

" Test for the mode() function
func Test_mode()
  new
  call append(0, ["Blue Ball Black", "Brown Band Bowl", ""])

  " Only complete from the current buffer.
  set complete=.

  inoremap <F2> <C-R>=Save_mode()<CR>
  xnoremap <F2> <Cmd>call Save_mode()<CR>

  normal! 3G
  exe "normal i\<F2>\<Esc>"
  call assert_equal('i-i', g:current_modes)
  " i_CTRL-P: Multiple matches
  exe "normal i\<C-G>uBa\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-P: Single match
  exe "normal iBro\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X
  exe "normal iBa\<C-X>\<F2>\<Esc>u"
  call assert_equal('i-ix', g:current_modes)
  " i_CTRL-X CTRL-P: Multiple matches
  exe "normal iBa\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-P: Single match
  exe "normal iBro\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-P + CTRL-P: Single match
  exe "normal iBro\<C-X>\<C-P>\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-L: Multiple matches
  exe "normal i\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-L: Single match
  exe "normal iBlu\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-P: No match
  exe "normal iCom\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-P: No match
  exe "normal iCom\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)
  " i_CTRL-X CTRL-L: No match
  exe "normal iabc\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('i-ic', g:current_modes)

  exe "normal R\<F2>\<Esc>"
  call assert_equal('R-R', g:current_modes)
  " R_CTRL-P: Multiple matches
  exe "normal RBa\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-P: Single match
  exe "normal RBro\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X
  exe "normal RBa\<C-X>\<F2>\<Esc>u"
  call assert_equal('R-Rx', g:current_modes)
  " R_CTRL-X CTRL-P: Multiple matches
  exe "normal RBa\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-P: Single match
  exe "normal RBro\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-P + CTRL-P: Single match
  exe "normal RBro\<C-X>\<C-P>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-L: Multiple matches
  exe "normal R\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-L: Single match
  exe "normal RBlu\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-P: No match
  exe "normal RCom\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-P: No match
  exe "normal RCom\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)
  " R_CTRL-X CTRL-L: No match
  exe "normal Rabc\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rc', g:current_modes)

  exe "normal gR\<F2>\<Esc>"
  call assert_equal('R-Rv', g:current_modes)
  " gR_CTRL-P: Multiple matches
  exe "normal gRBa\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-P: Single match
  exe "normal gRBro\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X
  exe "normal gRBa\<C-X>\<F2>\<Esc>u"
  call assert_equal('R-Rvx', g:current_modes)
  " gR_CTRL-X CTRL-P: Multiple matches
  exe "normal gRBa\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-P: Single match
  exe "normal gRBro\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-P + CTRL-P: Single match
  exe "normal gRBro\<C-X>\<C-P>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-L: Multiple matches
  exe "normal gR\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-L: Single match
  exe "normal gRBlu\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-P: No match
  exe "normal gRCom\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-P: No match
  exe "normal gRCom\<C-X>\<C-P>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)
  " gR_CTRL-X CTRL-L: No match
  exe "normal gRabc\<C-X>\<C-L>\<F2>\<Esc>u"
  call assert_equal('R-Rvc', g:current_modes)

  call assert_equal('n', 0->mode())
  call assert_equal('n', 1->mode())

  " i_CTRL-O
  exe "normal i\<C-O>:call Save_mode()\<Cr>\<Esc>"
  call assert_equal("n-niI", g:current_modes)

  " R_CTRL-O
  exe "normal R\<C-O>:call Save_mode()\<Cr>\<Esc>"
  call assert_equal("n-niR", g:current_modes)

  " gR_CTRL-O
  exe "normal gR\<C-O>:call Save_mode()\<Cr>\<Esc>"
  call assert_equal("n-niV", g:current_modes)

  " How to test operator-pending mode?

  call feedkeys("v", 'xt')
  call assert_equal('v', mode())
  call assert_equal('v', mode(1))
  call feedkeys("\<Esc>V", 'xt')
  call assert_equal('V', mode())
  call assert_equal('V', mode(1))
  call feedkeys("\<Esc>\<C-V>", 'xt')
  call assert_equal("\<C-V>", mode())
  call assert_equal("\<C-V>", mode(1))
  call feedkeys("\<Esc>", 'xt')

  call feedkeys("gh", 'xt')
  call assert_equal('s', mode())
  call assert_equal('s', mode(1))
  call feedkeys("\<Esc>gH", 'xt')
  call assert_equal('S', mode())
  call assert_equal('S', mode(1))
  call feedkeys("\<Esc>g\<C-H>", 'xt')
  call assert_equal("\<C-S>", mode())
  call assert_equal("\<C-S>", mode(1))
  call feedkeys("\<Esc>", 'xt')

  " v_CTRL-O
  exe "normal gh\<C-O>\<F2>\<Esc>"
  call assert_equal("v-vs", g:current_modes)
  exe "normal gH\<C-O>\<F2>\<Esc>"
  call assert_equal("V-Vs", g:current_modes)
  exe "normal g\<C-H>\<C-O>\<F2>\<Esc>"
  call assert_equal("\<C-V>-\<C-V>s", g:current_modes)

  call feedkeys(":echo \<C-R>=Save_mode()\<C-U>\<CR>", 'xt')
  call assert_equal('c-c', g:current_modes)
  call feedkeys("gQecho \<C-R>=Save_mode()\<CR>\<CR>vi\<CR>", 'xt')
  call assert_equal('c-cv', g:current_modes)
  call feedkeys("Qcall Save_mode()\<CR>vi\<CR>", 'xt')
  call assert_equal('c-ce', g:current_modes)
  " How to test Ex mode?

  " Test mode in operatorfunc (it used to be Operator-pending).
  set operatorfunc=OperatorFunc
  function OperatorFunc(_)
    call Save_mode()
  endfunction
  execute "normal! g@l\<Esc>"
  call assert_equal('n-n', g:current_modes)
  execute "normal! i\<C-o>g@l\<Esc>"
  call assert_equal('n-niI', g:current_modes)
  execute "normal! R\<C-o>g@l\<Esc>"
  call assert_equal('n-niR', g:current_modes)
  execute "normal! gR\<C-o>g@l\<Esc>"
  call assert_equal('n-niV', g:current_modes)

  if has('terminal')
    term
    call feedkeys("\<C-W>N", 'xt')
    call assert_equal('n', mode())
    call assert_equal('nt', mode(1))
    call feedkeys("aexit\<CR>", 'xt')
  endif

  bwipe!
  iunmap <F2>
  xunmap <F2>
  set complete&
  set operatorfunc&
  delfunction OperatorFunc
endfunc

" Test for append()
func Test_append()
  enew!
  split
  call assert_equal(0, append(1, []))
  call assert_equal(0, append(1, test_null_list()))
  call assert_equal(0, append(0, ["foo"]))
  call assert_equal(0, append(1, []))
  call assert_equal(0, append(1, test_null_list()))
  call assert_equal(0, append(8, []))
  call assert_equal(0, append(9, test_null_list()))
  call assert_equal(['foo', ''], getline(1, '$'))
  split
  only
  undo
  undo

  " Using $ instead of '$' must give an error
  call assert_fails("call append($, 'foobar')", 'E116:')

  call assert_fails("call append({}, '')", ['E728:', 'E728:'])
endfunc

" Test for setline()
func Test_setline()
  new
  call setline(0, ["foo"])
  call setline(0, [])
  call setline(0, test_null_list())
  call setline(1, ["bar"])
  call setline(1, [])
  call setline(1, test_null_list())
  call setline(2, [])
  call setline(2, test_null_list())
  call setline(3, [])
  call setline(3, test_null_list())
  call setline(2, ["baz"])
  call assert_equal(['bar', 'baz'], getline(1, '$'))
  close!
endfunc

func Test_getbufvar()
  let bnr = bufnr('%')
  let b:var_num = '1234'
  let def_num = '5678'
  call assert_equal('1234', getbufvar(bnr, 'var_num'))
  call assert_equal('1234', getbufvar(bnr, 'var_num', def_num))

  let bd = getbufvar(bnr, '')
  call assert_equal('1234', bd['var_num'])
  call assert_true(exists("bd['changedtick']"))
  call assert_equal(2, len(bd))

  let bd2 = getbufvar(bnr, '', def_num)
  call assert_equal(bd, bd2)

  unlet b:var_num
  call assert_equal(def_num, getbufvar(bnr, 'var_num', def_num))
  call assert_equal('', getbufvar(bnr, 'var_num'))

  let bd = getbufvar(bnr, '')
  call assert_equal(1, len(bd))
  let bd = getbufvar(bnr, '',def_num)
  call assert_equal(1, len(bd))

  call assert_equal('', getbufvar(9999, ''))
  call assert_equal(def_num, getbufvar(9999, '', def_num))
  unlet def_num

  call assert_equal(0, getbufvar(bnr, '&autoindent'))
  call assert_equal(0, getbufvar(bnr, '&autoindent', 1))

  " Set and get a buffer-local variable
  call setbufvar(bnr, 'bufvar_test', ['one', 'two'])
  call assert_equal(['one', 'two'], getbufvar(bnr, 'bufvar_test'))

  " Open new window with forced option values
  set fileformats=unix,dos
  new ++ff=dos ++bin ++enc=iso-8859-2
  call assert_equal('dos', getbufvar(bufnr('%'), '&fileformat'))
  call assert_equal(1, getbufvar(bufnr('%'), '&bin'))
  call assert_equal('iso-8859-2', getbufvar(bufnr('%'), '&fenc'))
  close

  " Get the b: dict.
  let b:testvar = 'one'
  new
  let b:testvar = 'two'
  let thebuf = bufnr()
  wincmd w
  call assert_equal('two', getbufvar(thebuf, 'testvar'))
  call assert_equal('two', getbufvar(thebuf, '').testvar)
  bwipe!

  set fileformats&
endfunc

func Test_last_buffer_nr()
  call assert_equal(bufnr('$'), last_buffer_nr())
endfunc

func Test_stridx()
  call assert_equal(-1, stridx('', 'l'))
  call assert_equal(0,  stridx('', ''))
  call assert_equal(0,  'hello'->stridx(''))
  call assert_equal(-1, stridx('hello', 'L'))
  call assert_equal(2,  stridx('hello', 'l', -1))
  call assert_equal(2,  stridx('hello', 'l', 0))
  call assert_equal(2,  'hello'->stridx('l', 1))
  call assert_equal(3,  stridx('hello', 'l', 3))
  call assert_equal(-1, stridx('hello', 'l', 4))
  call assert_equal(-1, stridx('hello', 'l', 10))
  call assert_equal(2,  stridx('hello', 'll'))
  call assert_equal(-1, stridx('hello', 'hello world'))
  call assert_fails("let n=stridx('hello', [])", 'E730:')
  call assert_fails("let n=stridx([], 'l')", 'E730:')
endfunc

func Test_strridx()
  call assert_equal(-1, strridx('', 'l'))
  call assert_equal(0,  strridx('', ''))
  call assert_equal(5,  strridx('hello', ''))
  call assert_equal(-1, strridx('hello', 'L'))
  call assert_equal(3,  'hello'->strridx('l'))
  call assert_equal(3,  strridx('hello', 'l', 10))
  call assert_equal(3,  strridx('hello', 'l', 3))
  call assert_equal(2,  strridx('hello', 'l', 2))
  call assert_equal(-1, strridx('hello', 'l', 1))
  call assert_equal(-1, strridx('hello', 'l', 0))
  call assert_equal(-1, strridx('hello', 'l', -1))
  call assert_equal(2,  strridx('hello', 'll'))
  call assert_equal(-1, strridx('hello', 'hello world'))
  call assert_fails("let n=strridx('hello', [])", 'E730:')
  call assert_fails("let n=strridx([], 'l')", 'E730:')
endfunc

func Test_match_func()
  call assert_equal(4,  match('testing', 'ing'))
  call assert_equal(4,  'testing'->match('ing', 2))
  call assert_equal(-1, match('testing', 'ing', 5))
  call assert_equal(-1, match('testing', 'ing', 8))
  call assert_equal(1, match(['vim', 'testing', 'execute'], 'ing'))
  call assert_equal(-1, match(['vim', 'testing', 'execute'], 'img'))
  call assert_fails("let x=match('vim', [])", 'E730:')
  call assert_equal(3, match(['a', 'b', 'c', 'a'], 'a', 1))
  call assert_equal(-1, match(['a', 'b', 'c', 'a'], 'a', 5))
  call assert_equal(4,  match('testing', 'ing', -1))
  call assert_fails("let x=match('testing', 'ing', 0, [])", 'E745:')
  call assert_equal(-1, match(test_null_list(), 2))
  call assert_equal(-1, match('abc', '\\%('))
endfunc

func Test_matchend()
  call assert_equal(7,  matchend('testing', 'ing'))
  call assert_equal(7,  'testing'->matchend('ing', 2))
  call assert_equal(-1, matchend('testing', 'ing', 5))
  call assert_equal(-1, matchend('testing', 'ing', 8))
  call assert_equal(match(['vim', 'testing', 'execute'], 'ing'), matchend(['vim', 'testing', 'execute'], 'ing'))
  call assert_equal(match(['vim', 'testing', 'execute'], 'img'), matchend(['vim', 'testing', 'execute'], 'img'))
endfunc

func Test_matchlist()
  call assert_equal(['acd', 'a', '', 'c', 'd', '', '', '', '', ''],  matchlist('acd', '\(a\)\?\(b\)\?\(c\)\?\(.*\)'))
  call assert_equal(['d', '', '', '', 'd', '', '', '', '', ''],  'acd'->matchlist('\(a\)\?\(b\)\?\(c\)\?\(.*\)', 2))
  call assert_equal([],  matchlist('acd', '\(a\)\?\(b\)\?\(c\)\?\(.*\)', 4))
endfunc

func Test_matchstr()
  call assert_equal('ing',  matchstr('testing', 'ing'))
  call assert_equal('ing',  'testing'->matchstr('ing', 2))
  call assert_equal('', matchstr('testing', 'ing', 5))
  call assert_equal('', matchstr('testing', 'ing', 8))
  call assert_equal('testing', matchstr(['vim', 'testing', 'execute'], 'ing'))
  call assert_equal('', matchstr(['vim', 'testing', 'execute'], 'img'))
endfunc

func Test_matchstrpos()
  call assert_equal(['ing', 4, 7], matchstrpos('testing', 'ing'))
  call assert_equal(['ing', 4, 7], 'testing'->matchstrpos('ing', 2))
  call assert_equal(['', -1, -1], matchstrpos('testing', 'ing', 5))
  call assert_equal(['', -1, -1], matchstrpos('testing', 'ing', 8))
  call assert_equal(['ing', 1, 4, 7], matchstrpos(['vim', 'testing', 'execute'], 'ing'))
  call assert_equal(['', -1, -1, -1], matchstrpos(['vim', 'testing', 'execute'], 'img'))
  call assert_equal(['', -1, -1], matchstrpos(test_null_list(), '\a'))
endfunc

func Test_nextnonblank_prevnonblank()
  new
insert
This


is

a
Test
.
  call assert_equal(0, nextnonblank(-1))
  call assert_equal(0, nextnonblank(0))
  call assert_equal(1, nextnonblank(1))
  call assert_equal(4, 2->nextnonblank())
  call assert_equal(4, nextnonblank(3))
  call assert_equal(4, nextnonblank(4))
  call assert_equal(6, nextnonblank(5))
  call assert_equal(6, nextnonblank(6))
  call assert_equal(7, nextnonblank(7))
  call assert_equal(0, 8->nextnonblank())

  call assert_equal(0, prevnonblank(-1))
  call assert_equal(0, prevnonblank(0))
  call assert_equal(1, 1->prevnonblank())
  call assert_equal(1, prevnonblank(2))
  call assert_equal(1, prevnonblank(3))
  call assert_equal(4, prevnonblank(4))
  call assert_equal(4, 5->prevnonblank())
  call assert_equal(6, prevnonblank(6))
  call assert_equal(7, prevnonblank(7))
  call assert_equal(0, prevnonblank(8))
  bw!
endfunc

func Test_byte2line_line2byte()
  new
  set endofline
  call setline(1, ['a', 'bc', 'd'])

  set fileformat=unix
  call assert_equal([-1, -1, 1, 1, 2, 2, 2, 3, 3, -1],
  \                 map(range(-1, 8), 'byte2line(v:val)'))
  call assert_equal([-1, -1, 1, 3, 6, 8, -1],
  \                 map(range(-1, 5), 'line2byte(v:val)'))

  set fileformat=mac
  call assert_equal([-1, -1, 1, 1, 2, 2, 2, 3, 3, -1],
  \                 map(range(-1, 8), 'v:val->byte2line()'))
  call assert_equal([-1, -1, 1, 3, 6, 8, -1],
  \                 map(range(-1, 5), 'v:val->line2byte()'))

  set fileformat=dos
  call assert_equal([-1, -1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, -1],
  \                 map(range(-1, 11), 'byte2line(v:val)'))
  call assert_equal([-1, -1, 1, 4, 8, 11, -1],
  \                 map(range(-1, 5), 'line2byte(v:val)'))

  bw!
  set noendofline nofixendofline
  normal a-
  for ff in ["unix", "mac", "dos"]
    let &fileformat = ff
    call assert_equal(1, line2byte(1))
    call assert_equal(2, line2byte(2))  " line2byte(line("$") + 1) is the buffer size plus one (as per :help line2byte).
  endfor

  set endofline& fixendofline& fileformat&
  bw!
endfunc

" Test for byteidx() using a character index
func Test_byteidx()
  let a = '.é.' " one char of two bytes
  call assert_equal(0, byteidx(a, 0))
  call assert_equal(1, byteidx(a, 1))
  call assert_equal(3, byteidx(a, 2))
  call assert_equal(4, byteidx(a, 3))
  call assert_equal(-1, byteidx(a, 4))

  let b = '.é.' " normal e with composing char
  call assert_equal(0, b->byteidx(0))
  call assert_equal(1, b->byteidx(1))
  call assert_equal(4, b->byteidx(2))
  call assert_equal(5, b->byteidx(3))
  call assert_equal(-1, b->byteidx(4))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  call assert_equal(0, byteidx(str, 0))
  call assert_equal(1, byteidx(str, 1))
  call assert_equal(6, byteidx(str, 2))
  call assert_equal(7, byteidx(str, 3))
  call assert_equal(12, byteidx(str, 4))
  call assert_equal(-1, byteidx(str, 5))

  " empty string
  call assert_equal(0, byteidx('', 0))
  call assert_equal(-1, byteidx('', 1))

  " error cases
  call assert_fails("call byteidx([], 0)", 'E730:')
  call assert_fails("call byteidx('abc', [])", 'E745:')
  call assert_fails("call byteidx('abc', 0, {})", ['E728:', 'E728:'])
  call assert_fails("call byteidx('abc', 0, -1)", ['E1023:', 'E1023:'])
endfunc

" Test for byteidxcomp() using a character index
func Test_byteidxcomp()
  let a = '.é.' " one char of two bytes
  call assert_equal(0, byteidxcomp(a, 0))
  call assert_equal(1, byteidxcomp(a, 1))
  call assert_equal(3, byteidxcomp(a, 2))
  call assert_equal(4, byteidxcomp(a, 3))
  call assert_equal(-1, byteidxcomp(a, 4))

  let b = '.é.' " normal e with composing char
  call assert_equal(0, b->byteidxcomp(0))
  call assert_equal(1, b->byteidxcomp(1))
  call assert_equal(2, b->byteidxcomp(2))
  call assert_equal(4, b->byteidxcomp(3))
  call assert_equal(5, b->byteidxcomp(4))
  call assert_equal(-1, b->byteidxcomp(5))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  call assert_equal(0, byteidxcomp(str, 0))
  call assert_equal(1, byteidxcomp(str, 1))
  call assert_equal(2, byteidxcomp(str, 2))
  call assert_equal(4, byteidxcomp(str, 3))
  call assert_equal(6, byteidxcomp(str, 4))
  call assert_equal(7, byteidxcomp(str, 5))
  call assert_equal(8, byteidxcomp(str, 6))
  call assert_equal(10, byteidxcomp(str, 7))
  call assert_equal(12, byteidxcomp(str, 8))
  call assert_equal(-1, byteidxcomp(str, 9))

  " empty string
  call assert_equal(0, byteidxcomp('', 0))
  call assert_equal(-1, byteidxcomp('', 1))

  " error cases
  call assert_fails("call byteidxcomp([], 0)", 'E730:')
  call assert_fails("call byteidxcomp('abc', [])", 'E745:')
  call assert_fails("call byteidxcomp('abc', 0, {})", ['E728:', 'E728:'])
  call assert_fails("call byteidxcomp('abc', 0, -1)", ['E1023:', 'E1023:'])
endfunc

" Test for byteidx() using a UTF-16 index
func Test_byteidx_from_utf16_index()
  " string with single byte characters
  let str = "abc"
  for i in range(3)
    call assert_equal(i, byteidx(str, i, v:true))
  endfor
  call assert_equal(3, byteidx(str, 3, v:true))
  call assert_equal(-1, byteidx(str, 4, v:true))

  " string with two byte characters
  let str = "a©©b"
  call assert_equal(0, byteidx(str, 0, v:true))
  call assert_equal(1, byteidx(str, 1, v:true))
  call assert_equal(3, byteidx(str, 2, v:true))
  call assert_equal(5, byteidx(str, 3, v:true))
  call assert_equal(6, byteidx(str, 4, v:true))
  call assert_equal(-1, byteidx(str, 5, v:true))

  " string with two byte characters
  let str = "a😊😊b"
  call assert_equal(0, byteidx(str, 0, v:true))
  call assert_equal(1, byteidx(str, 1, v:true))
  call assert_equal(1, byteidx(str, 2, v:true))
  call assert_equal(5, byteidx(str, 3, v:true))
  call assert_equal(5, byteidx(str, 4, v:true))
  call assert_equal(9, byteidx(str, 5, v:true))
  call assert_equal(10, byteidx(str, 6, v:true))
  call assert_equal(-1, byteidx(str, 7, v:true))

  " string with composing characters
  let str = '-á-b́'
  call assert_equal(0, byteidx(str, 0, v:true))
  call assert_equal(1, byteidx(str, 1, v:true))
  call assert_equal(4, byteidx(str, 2, v:true))
  call assert_equal(5, byteidx(str, 3, v:true))
  call assert_equal(8, byteidx(str, 4, v:true))
  call assert_equal(-1, byteidx(str, 5, v:true))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  call assert_equal(0, byteidx(str, 0, v:true))
  call assert_equal(1, byteidx(str, 1, v:true))
  call assert_equal(6, byteidx(str, 2, v:true))
  call assert_equal(7, byteidx(str, 3, v:true))
  call assert_equal(12, byteidx(str, 4, v:true))
  call assert_equal(-1, byteidx(str, 5, v:true))

  " empty string
  call assert_equal(0, byteidx('', 0, v:true))
  call assert_equal(-1, byteidx('', 1, v:true))

  " error cases
  call assert_fails('call byteidx(str, 0, [])', 'E745:')
endfunc

" Test for byteidxcomp() using a UTF-16 index
func Test_byteidxcomp_from_utf16_index()
  " string with single byte characters
  let str = "abc"
  for i in range(3)
    call assert_equal(i, byteidxcomp(str, i, v:true))
  endfor
  call assert_equal(3, byteidxcomp(str, 3, v:true))
  call assert_equal(-1, byteidxcomp(str, 4, v:true))

  " string with two byte characters
  let str = "a©©b"
  call assert_equal(0, byteidxcomp(str, 0, v:true))
  call assert_equal(1, byteidxcomp(str, 1, v:true))
  call assert_equal(3, byteidxcomp(str, 2, v:true))
  call assert_equal(5, byteidxcomp(str, 3, v:true))
  call assert_equal(6, byteidxcomp(str, 4, v:true))
  call assert_equal(-1, byteidxcomp(str, 5, v:true))

  " string with two byte characters
  let str = "a😊😊b"
  call assert_equal(0, byteidxcomp(str, 0, v:true))
  call assert_equal(1, byteidxcomp(str, 1, v:true))
  call assert_equal(1, byteidxcomp(str, 2, v:true))
  call assert_equal(5, byteidxcomp(str, 3, v:true))
  call assert_equal(5, byteidxcomp(str, 4, v:true))
  call assert_equal(9, byteidxcomp(str, 5, v:true))
  call assert_equal(10, byteidxcomp(str, 6, v:true))
  call assert_equal(-1, byteidxcomp(str, 7, v:true))

  " string with composing characters
  let str = '-á-b́'
  call assert_equal(0, byteidxcomp(str, 0, v:true))
  call assert_equal(1, byteidxcomp(str, 1, v:true))
  call assert_equal(2, byteidxcomp(str, 2, v:true))
  call assert_equal(4, byteidxcomp(str, 3, v:true))
  call assert_equal(5, byteidxcomp(str, 4, v:true))
  call assert_equal(6, byteidxcomp(str, 5, v:true))
  call assert_equal(8, byteidxcomp(str, 6, v:true))
  call assert_equal(-1, byteidxcomp(str, 7, v:true))
  call assert_fails('call byteidxcomp(str, 0, [])', 'E745:')

  " string with multiple composing characters
  let str = '-ą́-ą́'
  call assert_equal(0, byteidxcomp(str, 0, v:true))
  call assert_equal(1, byteidxcomp(str, 1, v:true))
  call assert_equal(2, byteidxcomp(str, 2, v:true))
  call assert_equal(4, byteidxcomp(str, 3, v:true))
  call assert_equal(6, byteidxcomp(str, 4, v:true))
  call assert_equal(7, byteidxcomp(str, 5, v:true))
  call assert_equal(8, byteidxcomp(str, 6, v:true))
  call assert_equal(10, byteidxcomp(str, 7, v:true))
  call assert_equal(12, byteidxcomp(str, 8, v:true))
  call assert_equal(-1, byteidxcomp(str, 9, v:true))

  " empty string
  call assert_equal(0, byteidxcomp('', 0, v:true))
  call assert_equal(-1, byteidxcomp('', 1, v:true))

  " error cases
  call assert_fails('call byteidxcomp(str, 0, [])', 'E745:')
endfunc

" Test for charidx() using a byte index
func Test_charidx()
  let a = 'xáb́y'
  call assert_equal(0, charidx(a, 0))
  call assert_equal(1, charidx(a, 3))
  call assert_equal(2, charidx(a, 4))
  call assert_equal(3, charidx(a, 7))
  call assert_equal(-1, charidx(a, 8))
  call assert_equal(-1, charidx(a, -1))

  " count composing characters
  call assert_equal(0, a->charidx(0, 1))
  call assert_equal(2, a->charidx(2, 1))
  call assert_equal(3, a->charidx(4, 1))
  call assert_equal(5, a->charidx(7, 1))
  call assert_equal(-1, a->charidx(8, 1))

  " empty string
  call assert_equal(-1, charidx('', 0))
  call assert_equal(-1, charidx('', 0, 1))

  " error cases
  call assert_equal(-1, charidx(test_null_string(), 0))
  call assert_fails('let x = charidx([], 1)', 'E1174:')
  call assert_fails('let x = charidx("abc", [])', 'E1210:')
  call assert_fails('let x = charidx("abc", 1, [])', 'E1212:')
  call assert_fails('let x = charidx("abc", 1, -1)', 'E1212:')
  call assert_fails('let x = charidx("abc", 1, 2)', 'E1212:')
endfunc

" Test for charidx() using a UTF-16 index
func Test_charidx_from_utf16_index()
  " string with single byte characters
  let str = "abc"
  for i in range(3)
    call assert_equal(i, charidx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, charidx(str, 3, v:false, v:true))

  " string with two byte characters
  let str = "a©©b"
  call assert_equal(0, charidx(str, 0, v:false, v:true))
  call assert_equal(1, charidx(str, 1, v:false, v:true))
  call assert_equal(2, charidx(str, 2, v:false, v:true))
  call assert_equal(3, charidx(str, 3, v:false, v:true))
  call assert_equal(-1, charidx(str, 4, v:false, v:true))

  " string with four byte characters
  let str = "a😊😊b"
  call assert_equal(0, charidx(str, 0, v:false, v:true))
  call assert_equal(1, charidx(str, 1, v:false, v:true))
  call assert_equal(1, charidx(str, 2, v:false, v:true))
  call assert_equal(2, charidx(str, 3, v:false, v:true))
  call assert_equal(2, charidx(str, 4, v:false, v:true))
  call assert_equal(3, charidx(str, 5, v:false, v:true))
  call assert_equal(-1, charidx(str, 6, v:false, v:true))

  " string with composing characters
  let str = '-á-b́'
  for i in str->strcharlen()->range()
    call assert_equal(i, charidx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, charidx(str, 4, v:false, v:true))
  for i in str->strchars()->range()
    call assert_equal(i, charidx(str, i, v:true, v:true))
  endfor
  call assert_equal(-1, charidx(str, 6, v:true, v:true))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  for i in str->strcharlen()->range()
    call assert_equal(i, charidx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, charidx(str, 4, v:false, v:true))
  for i in str->strchars()->range()
    call assert_equal(i, charidx(str, i, v:true, v:true))
  endfor
  call assert_equal(-1, charidx(str, 8, v:true, v:true))

  " empty string
  call assert_equal(-1, charidx('', 0, v:false, v:true))
  call assert_equal(-1, charidx('', 0, v:true, v:true))

  " error cases
  call assert_equal(-1, charidx('', 0, v:false, v:true))
  call assert_equal(-1, charidx('', 0, v:true, v:true))
  call assert_equal(-1, charidx(test_null_string(), 0, v:false, v:true))
  call assert_fails('let x = charidx("abc", 1, v:false, [])', 'E1212:')
  call assert_fails('let x = charidx("abc", 1, v:true, [])', 'E1212:')
endfunc

" Test for utf16idx() using a byte index
func Test_utf16idx_from_byteidx()
  " UTF-16 index of a string with single byte characters
  let str = "abc"
  for i in range(3)
    call assert_equal(i, utf16idx(str, i))
  endfor
  call assert_equal(-1, utf16idx(str, 3))

  " UTF-16 index of a string with two byte characters
  let str = 'a©©b'
  call assert_equal(0, str->utf16idx(0))
  call assert_equal(1, str->utf16idx(1))
  call assert_equal(1, str->utf16idx(2))
  call assert_equal(2, str->utf16idx(3))
  call assert_equal(2, str->utf16idx(4))
  call assert_equal(3, str->utf16idx(5))
  call assert_equal(-1, str->utf16idx(6))

  " UTF-16 index of a string with four byte characters
  let str = 'a😊😊b'
  call assert_equal(0, utf16idx(str, 0))
  call assert_equal(2, utf16idx(str, 1))
  call assert_equal(2, utf16idx(str, 2))
  call assert_equal(2, utf16idx(str, 3))
  call assert_equal(2, utf16idx(str, 4))
  call assert_equal(4, utf16idx(str, 5))
  call assert_equal(4, utf16idx(str, 6))
  call assert_equal(4, utf16idx(str, 7))
  call assert_equal(4, utf16idx(str, 8))
  call assert_equal(5, utf16idx(str, 9))
  call assert_equal(-1, utf16idx(str, 10))

  " UTF-16 index of a string with composing characters
  let str = '-á-b́'
  call assert_equal(0, utf16idx(str, 0))
  call assert_equal(1, utf16idx(str, 1))
  call assert_equal(1, utf16idx(str, 2))
  call assert_equal(1, utf16idx(str, 3))
  call assert_equal(2, utf16idx(str, 4))
  call assert_equal(3, utf16idx(str, 5))
  call assert_equal(3, utf16idx(str, 6))
  call assert_equal(3, utf16idx(str, 7))
  call assert_equal(-1, utf16idx(str, 8))
  call assert_equal(0, utf16idx(str, 0, v:true))
  call assert_equal(1, utf16idx(str, 1, v:true))
  call assert_equal(2, utf16idx(str, 2, v:true))
  call assert_equal(2, utf16idx(str, 3, v:true))
  call assert_equal(3, utf16idx(str, 4, v:true))
  call assert_equal(4, utf16idx(str, 5, v:true))
  call assert_equal(5, utf16idx(str, 6, v:true))
  call assert_equal(5, utf16idx(str, 7, v:true))
  call assert_equal(-1, utf16idx(str, 8, v:true))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  call assert_equal(0, utf16idx(str, 0))
  call assert_equal(1, utf16idx(str, 1))
  call assert_equal(1, utf16idx(str, 2))
  call assert_equal(1, utf16idx(str, 3))
  call assert_equal(1, utf16idx(str, 4))
  call assert_equal(1, utf16idx(str, 5))
  call assert_equal(2, utf16idx(str, 6))
  call assert_equal(3, utf16idx(str, 7))
  call assert_equal(3, utf16idx(str, 8))
  call assert_equal(3, utf16idx(str, 9))
  call assert_equal(3, utf16idx(str, 10))
  call assert_equal(3, utf16idx(str, 11))
  call assert_equal(-1, utf16idx(str, 12))
  call assert_equal(0, utf16idx(str, 0, v:true))
  call assert_equal(1, utf16idx(str, 1, v:true))
  call assert_equal(2, utf16idx(str, 2, v:true))
  call assert_equal(2, utf16idx(str, 3, v:true))
  call assert_equal(3, utf16idx(str, 4, v:true))
  call assert_equal(3, utf16idx(str, 5, v:true))
  call assert_equal(4, utf16idx(str, 6, v:true))
  call assert_equal(5, utf16idx(str, 7, v:true))
  call assert_equal(6, utf16idx(str, 8, v:true))
  call assert_equal(6, utf16idx(str, 9, v:true))
  call assert_equal(7, utf16idx(str, 10, v:true))
  call assert_equal(7, utf16idx(str, 11, v:true))
  call assert_equal(-1, utf16idx(str, 12, v:true))

  " empty string
  call assert_equal(-1, utf16idx('', 0))
  call assert_equal(-1, utf16idx('', 0, v:true))

  " error cases
  call assert_equal(-1, utf16idx("", 0))
  call assert_equal(-1, utf16idx("abc", -1))
  call assert_equal(-1, utf16idx(test_null_string(), 0))
  call assert_fails('let l = utf16idx([], 0)', 'E1174:')
  call assert_fails('let l = utf16idx("ab", [])', 'E1210:')
  call assert_fails('let l = utf16idx("ab", 0, [])', 'E1212:')
endfunc

" Test for utf16idx() using a character index
func Test_utf16idx_from_charidx()
  let str = "abc"
  for i in str->strcharlen()->range()
    call assert_equal(i, utf16idx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 3, v:false, v:true))

  " UTF-16 index of a string with two byte characters
  let str = "a©©b"
  for i in str->strcharlen()->range()
    call assert_equal(i, utf16idx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 4, v:false, v:true))

  " UTF-16 index of a string with four byte characters
  let str = "a😊😊b"
  call assert_equal(0, utf16idx(str, 0, v:false, v:true))
  call assert_equal(2, utf16idx(str, 1, v:false, v:true))
  call assert_equal(4, utf16idx(str, 2, v:false, v:true))
  call assert_equal(5, utf16idx(str, 3, v:false, v:true))
  call assert_equal(-1, utf16idx(str, 4, v:false, v:true))

  " UTF-16 index of a string with composing characters
  let str = '-á-b́'
  for i in str->strcharlen()->range()
    call assert_equal(i, utf16idx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 4, v:false, v:true))
  for i in str->strchars()->range()
    call assert_equal(i, utf16idx(str, i, v:true, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 6, v:true, v:true))

  " string with multiple composing characters
  let str = '-ą́-ą́'
  for i in str->strcharlen()->range()
    call assert_equal(i, utf16idx(str, i, v:false, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 4, v:false, v:true))
  for i in str->strchars()->range()
    call assert_equal(i, utf16idx(str, i, v:true, v:true))
  endfor
  call assert_equal(-1, utf16idx(str, 8, v:true, v:true))

  " empty string
  call assert_equal(-1, utf16idx('', 0, v:false, v:true))
  call assert_equal(-1, utf16idx('', 0, v:true, v:true))

  " error cases
  call assert_equal(-1, utf16idx(test_null_string(), 0, v:true, v:true))
  call assert_fails('let l = utf16idx("ab", 0, v:false, [])', 'E1212:')
endfunc

" Test for strutf16len()
func Test_strutf16len()
  call assert_equal(3, strutf16len('abc'))
  call assert_equal(3, 'abc'->strutf16len(v:true))
  call assert_equal(4, strutf16len('a©©b'))
  call assert_equal(4, strutf16len('a©©b', v:true))
  call assert_equal(6, strutf16len('a😊😊b'))
  call assert_equal(6, strutf16len('a😊😊b', v:true))
  call assert_equal(4, strutf16len('-á-b́'))
  call assert_equal(6, strutf16len('-á-b́', v:true))
  call assert_equal(4, strutf16len('-ą́-ą́'))
  call assert_equal(8, strutf16len('-ą́-ą́', v:true))
  call assert_equal(0, strutf16len(''))

  " error cases
  call assert_fails('let l = strutf16len([])', 'E1174:')
  call assert_fails('let l = strutf16len("a", [])', 'E1212:')
  call assert_equal(0, strutf16len(test_null_string()))
endfunc

func Test_count()
  let l = ['a', 'a', 'A', 'b']
  call assert_equal(2, count(l, 'a'))
  call assert_equal(1, count(l, 'A'))
  call assert_equal(1, count(l, 'b'))
  call assert_equal(0, count(l, 'B'))

  call assert_equal(2, count(l, 'a', 0))
  call assert_equal(1, count(l, 'A', 0))
  call assert_equal(1, count(l, 'b', 0))
  call assert_equal(0, count(l, 'B', 0))

  call assert_equal(3, count(l, 'a', 1))
  call assert_equal(3, count(l, 'A', 1))
  call assert_equal(1, count(l, 'b', 1))
  call assert_equal(1, count(l, 'B', 1))
  call assert_equal(0, count(l, 'c', 1))

  call assert_equal(1, count(l, 'a', 0, 1))
  call assert_equal(2, count(l, 'a', 1, 1))
  call assert_fails('call count(l, "a", 0, 10)', 'E684:')
  call assert_fails('call count(l, "a", [])', 'E745:')

  let d = {1: 'a', 2: 'a', 3: 'A', 4: 'b'}
  call assert_equal(2, count(d, 'a'))
  call assert_equal(1, count(d, 'A'))
  call assert_equal(1, count(d, 'b'))
  call assert_equal(0, count(d, 'B'))

  call assert_equal(2, count(d, 'a', 0))
  call assert_equal(1, count(d, 'A', 0))
  call assert_equal(1, count(d, 'b', 0))
  call assert_equal(0, count(d, 'B', 0))

  call assert_equal(3, count(d, 'a', 1))
  call assert_equal(3, count(d, 'A', 1))
  call assert_equal(1, count(d, 'b', 1))
  call assert_equal(1, count(d, 'B', 1))
  call assert_equal(0, count(d, 'c', 1))

  call assert_fails('call count(d, "a", 0, 1)', 'E474:')

  call assert_equal(0, count("foo", "bar"))
  call assert_equal(1, count("foo", "oo"))
  call assert_equal(2, count("foo", "o"))
  call assert_equal(0, count("foo", "O"))
  call assert_equal(2, count("foo", "O", 1))
  call assert_equal(2, count("fooooo", "oo"))
  call assert_equal(0, count("foo", ""))

  call assert_fails('call count(0, 0)', 'E712:')
endfunc

func Test_changenr()
  new Xchangenr
  call assert_equal(0, changenr())
  norm ifoo
  call assert_equal(1, changenr())
  set undolevels=10
  norm Sbar
  call assert_equal(2, changenr())
  undo
  call assert_equal(1, changenr())
  redo
  call assert_equal(2, changenr())
  bw!
  set undolevels&
endfunc

func Test_filewritable()
  new Xfilewritable
  write!
  call assert_equal(1, filewritable('Xfilewritable'))

  call assert_notequal(0, setfperm('Xfilewritable', 'r--r-----'))
  call assert_equal(0, filewritable('Xfilewritable'))

  call assert_notequal(0, setfperm('Xfilewritable', 'rw-r-----'))
  call assert_equal(1, 'Xfilewritable'->filewritable())

  call assert_equal(0, filewritable('doesnotexist'))

  call mkdir('Xwritedir', 'D')
  call assert_equal(2, filewritable('Xwritedir'))

  call delete('Xfilewritable')
  bw!
endfunc

func Test_Executable()
  if has('win32')
    call assert_equal(1, executable('notepad'))
    call assert_equal(1, 'notepad.exe'->executable())
    call assert_equal(0, executable('notepad.exe.exe'))
    call assert_equal(0, executable('shell32.dll'))
    call assert_equal(0, executable('win.ini'))

    " get "notepad" path and remove the leading drive and sep. (ex. 'C:\')
    let notepadcmd = exepath('notepad.exe')
    let driveroot = notepadcmd[:2]
    let notepadcmd = notepadcmd[3:]
    new
    " check that the relative path works in /
    execute 'lcd' driveroot
    call assert_equal(1, executable(notepadcmd))
    call assert_equal(driveroot .. notepadcmd, notepadcmd->exepath())
    bwipe

    " create "notepad.bat"
    call mkdir('Xnotedir')
    let notepadbat = fnamemodify('Xnotedir/notepad.bat', ':p')
    call writefile([], notepadbat)
    new
    " check that the path and the pathext order is valid
    lcd Xnotedir
    let [pathext, $PATHEXT] = [$PATHEXT, '.com;.exe;.bat;.cmd']
    call assert_equal(notepadbat, exepath('notepad'))
    let $PATHEXT = pathext
    bwipe
    eval 'Xnotedir'->delete('rf')
  elseif has('unix')
    call assert_equal(1, 'cat'->executable())
    call assert_equal(0, executable('nodogshere'))

    " get "cat" path and remove the leading /
    let catcmd = exepath('cat')[1:]
    new
    " check that the relative path works in /
    lcd /
    call assert_equal(1, executable(catcmd))
    let result = catcmd->exepath()
    " when using chroot looking for sbin/cat can return bin/cat, that is OK
    if catcmd =~ '\<sbin\>' && result =~ '\<bin\>'
      call assert_equal('/' .. substitute(catcmd, '\<sbin\>', 'bin', ''), result)
    else
      " /bin/cat and /usr/bin/cat may be hard linked, we could get either
      let result = substitute(result, '/usr/bin/cat', '/bin/cat', '')
      let catcmd = substitute(catcmd, 'usr/bin/cat', 'bin/cat', '')
      call assert_equal('/' .. catcmd, result)
    endif
    bwipe
  else
    throw 'Skipped: does not work on this platform'
  endif
endfunc

func Test_executable_windows_store_apps()
  CheckMSWindows

  " Windows Store apps install some 'decoy' .exe that require some careful
  " handling as they behave similarly to symlinks.
  let app_dir = expand("$LOCALAPPDATA\\Microsoft\\WindowsApps")
  if !isdirectory(app_dir)
    return
  endif

  let save_path = $PATH
  let $PATH = app_dir
  " Ensure executable() finds all the app .exes
  for entry in readdir(app_dir)
    if entry =~ '\.exe$'
      call assert_true(executable(entry))
    endif
  endfor

  let $PATH = save_path
endfunc

func Test_executable_longname()
  CheckMSWindows

  " Create a temporary .bat file with 205 characters in the name.
  " Maximum length of a filename (including the path) on MS-Windows is 259
  " characters.
  " See https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
  let len = 259 - getcwd()->len() - 6
  if len > 200
    let len = 200
  endif

  let fname = 'X' . repeat('あ', len) . '.bat'
  call writefile([], fname)
  call assert_equal(1, executable(fname))
  call delete(fname)
endfunc

func Test_hostname()
  let hostname_vim = hostname()
  if has('unix')
    let hostname_system = systemlist('uname -n')[0]
    call assert_equal(hostname_vim, hostname_system)
  endif
endfunc

func Test_getpid()
  " getpid() always returns the same value within a vim instance.
  call assert_equal(getpid(), getpid())
  if has('unix')
    call assert_equal(systemlist('echo $PPID')[0], string(getpid()))
  endif
endfunc

func Test_hlexists()
  call assert_equal(0, hlexists('does_not_exist'))
  call assert_equal(0, 'Number'->hlexists())
  call assert_equal(0, highlight_exists('does_not_exist'))
  call assert_equal(0, highlight_exists('Number'))
  syntax on
  call assert_equal(0, hlexists('does_not_exist'))
  call assert_equal(1, hlexists('Number'))
  call assert_equal(0, highlight_exists('does_not_exist'))
  call assert_equal(1, highlight_exists('Number'))
  syntax off
endfunc

" Test for the col() function
func Test_col()
  new
  call setline(1, 'abcdef')
  norm gg4|mx6|mY2|
  call assert_equal(2, col('.'))
  call assert_equal(7, col('$'))
  call assert_equal(2, col('v'))
  call assert_equal(4, col("'x"))
  call assert_equal(6, col("'Y"))
  call assert_equal(2, [1, 2]->col())
  call assert_equal(7, col([1, '$']))

  call assert_equal(0, col(''))
  call assert_equal(0, col('x'))
  call assert_equal(0, col([2, '$']))
  call assert_equal(0, col([1, 100]))
  call assert_equal(0, col([1]))
  call assert_equal(0, col(test_null_list()))
  call assert_fails('let c = col({})', 'E1222:')
  call assert_fails('let c = col(".", [])', 'E1210:')

  " test for getting the visual start column
  func T()
    let g:Vcol = col('v')
    return ''
  endfunc
  let g:Vcol = 0
  xmap <expr> <F2> T()
  exe "normal gg3|ve\<F2>"
  call assert_equal(3, g:Vcol)
  xunmap <F2>
  delfunc T

  " Test for the visual line start and end marks '< and '>
  call setline(1, ['one', 'one two', 'one two three'])
  "normal! ggVG
  call feedkeys("ggVG\<Esc>", 'xt')
  call assert_equal(1, col("'<"))
  call assert_equal(14, col("'>"))
  " Delete the last line of the visually selected region
  $d
  call assert_notequal(14, col("'>"))

  " Test with 'virtualedit'
  set virtualedit=all
  call cursor(1, 10)
  call assert_equal(4, col('.'))
  set virtualedit&

  " Test for getting the column number in another window
  let winid = win_getid()
  new
  call win_execute(winid, 'normal 1G$')
  call assert_equal(3, col('.', winid))
  call win_execute(winid, 'normal 2G')
  call assert_equal(8, col('$', winid))
  call assert_equal(0, col('.', 5001))

  bw!
endfunc

" Test for input()
func Test_input_func()
  " Test for prompt with multiple lines
  redir => v
  call feedkeys(":let c = input(\"A\\nB\\nC\\n? \")\<CR>B\<CR>", 'xt')
  redir END
  call assert_equal("B", c)
  call assert_equal(['A', 'B', 'C'], split(v, "\n"))

  " Test for default value
  call feedkeys(":let c = input('color? ', 'red')\<CR>\<CR>", 'xt')
  call assert_equal('red', c)

  " Test for completion at the input prompt
  func! Tcomplete(arglead, cmdline, pos)
    return "item1\nitem2\nitem3"
  endfunc
  call feedkeys(":let c = input('Q? ', '', 'custom,Tcomplete')\<CR>"
        \ .. "\<C-A>\<CR>", 'xt')
  delfunc Tcomplete
  call assert_equal('item1 item2 item3', c)

  " Test for using special characters as default input
  call feedkeys(":let c = input('name? ', \"x\\<BS>y\")\<CR>\<CR>", 'xt')
  call assert_equal('y', c)

  " Test for using text with composing characters as default input
  call feedkeys(":let c = input('name? ', \"ã̳\")\<CR>\<CR>", 'xt')
  call assert_equal('ã̳', c)

  " Test for using <CR> as default input
  call feedkeys(":let c = input('name? ', \"\\<CR>\")\<CR>x\<CR>", 'xt')
  call assert_equal(' x', c)

  call assert_fails("call input('F:', '', 'invalid')", 'E180:')
  call assert_fails("call input('F:', '', [])", 'E730:')
endfunc

" Test for the inputdialog() function
func Test_inputdialog()
  set timeout timeoutlen=10
  if has('gui_running')
    call assert_fails('let v=inputdialog([], "xx")', 'E730:')
    call assert_fails('let v=inputdialog("Q", [])', 'E730:')
  else
    call feedkeys(":let v=inputdialog('Q:', 'xx', 'yy')\<CR>\<CR>", 'xt')
    call assert_equal('xx', v)
    call feedkeys(":let v=inputdialog('Q:', 'xx', 'yy')\<CR>\<Esc>", 'xt')
    call assert_equal('yy', v)
  endif
  set timeout& timeoutlen&
endfunc

" Test for inputlist()
func Test_inputlist()
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>1\<cr>", 'tx')
  call assert_equal(1, c)
  call feedkeys(":let c = ['Select color:', '1. red', '2. green', '3. blue']->inputlist()\<cr>2\<cr>", 'tx')
  call assert_equal(2, c)
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>3\<cr>", 'tx')
  call assert_equal(3, c)

  " CR to cancel
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>\<cr>", 'tx')
  call assert_equal(0, c)

  " Esc to cancel
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>\<Esc>", 'tx')
  call assert_equal(0, c)

  " q to cancel
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>q", 'tx')
  call assert_equal(0, c)

  " Cancel after inputting a number
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>5q", 'tx')
  call assert_equal(0, c)

  " Use backspace to delete characters in the prompt
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>1\<BS>3\<BS>2\<cr>", 'tx')
  call assert_equal(2, c)

  " Use mouse to make a selection
  call test_setmouse(&lines - 3, 2)
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>\<LeftMouse>", 'tx')
  call assert_equal(1, c)
  " Mouse click outside of the list
  call test_setmouse(&lines - 6, 2)
  call feedkeys(":let c = inputlist(['Select color:', '1. red', '2. green', '3. blue'])\<cr>\<LeftMouse>", 'tx')
  call assert_equal(-2, c)

  call assert_fails('call inputlist("")', 'E686:')
  call assert_fails('call inputlist(test_null_list())', 'E686:')
endfunc

func Test_range_inputlist()
  " flush out any garbage left in the buffer
  while getchar(0)
  endwhile

  call feedkeys(":let result = inputlist(range(10))\<CR>1\<CR>", 'x')
  call assert_equal(1, result)
  call feedkeys(":let result = inputlist(range(3, 10))\<CR>1\<CR>", 'x')
  call assert_equal(1, result)

  unlet result
endfunc

func Test_balloon_show()
  CheckFeature balloon_eval

  " This won't do anything but must not crash either.
  call balloon_show('hi!')
  if !has('gui_running')
    call balloon_show(range(3))
    call balloon_show([])
  endif
endfunc

func Test_setbufvar_options()
  " This tests that aucmd_prepbuf() and aucmd_restbuf() properly restore the
  " window layout and cursor position.
  call assert_equal(1, winnr('$'))
  split dummy_preview
  resize 2
  set winfixheight winfixwidth
  let prev_id = win_getid()

  wincmd j
  let wh = winheight(0)
  let dummy_buf = bufnr('dummy_buf1', v:true)
  call setbufvar(dummy_buf, '&buftype', 'nofile')
  execute 'belowright vertical split #' . dummy_buf
  call assert_equal(wh, winheight(0))
  let dum1_id = win_getid()
  call setline(1, 'foo')
  normal! V$
  call assert_equal(4, col('.'))
  call setbufvar('dummy_preview', '&buftype', 'nofile')
  call assert_equal(4, col('.'))

  wincmd h
  let wh = winheight(0)
  call setline(1, 'foo')
  normal! V$
  call assert_equal(4, col('.'))
  let dummy_buf = bufnr('dummy_buf2', v:true)
  eval 'nofile'->setbufvar(dummy_buf, '&buftype')
  call assert_equal(4, col('.'))
  execute 'belowright vertical split #' . dummy_buf
  call assert_equal(wh, winheight(0))

  bwipe!
  call win_gotoid(prev_id)
  bwipe!
  call win_gotoid(dum1_id)
  bwipe!
endfunc

func Test_setbufvar_keep_window_title()
  CheckRunVimInTerminal
  if !has('title') || empty(&t_ts)
    throw "Skipped: can't get/set title"
  endif

  let lines =<< trim END
      set title
      edit Xa.txt
      let g:buf = bufadd('Xb.txt')
      inoremap <F2> <C-R>=setbufvar(g:buf, '&autoindent', 1) ?? ''<CR>
  END
  call writefile(lines, 'Xsetbufvar', 'D')
  let buf = RunVimInTerminal('-S Xsetbufvar', {})
  call WaitForAssert({-> assert_match('Xa.txt', term_gettitle(buf))}, 1000)

  call term_sendkeys(buf, "i\<F2>")
  call TermWait(buf)
  call term_sendkeys(buf, "\<Esc>")
  call TermWait(buf)
  call assert_match('Xa.txt', term_gettitle(buf))

  call StopVimInTerminal(buf)
endfunc

func Test_redo_in_nested_functions()
  nnoremap g. :set opfunc=Operator<CR>g@
  function Operator( type, ... )
     let @x = 'XXX'
     execute 'normal! g`[' . (a:type ==# 'line' ? 'V' : 'v') . 'g`]' . '"xp'
  endfunction

  function! Apply()
      5,6normal! .
  endfunction

  new
  call setline(1, repeat(['some "quoted" text', 'more "quoted" text'], 3))
  1normal g.i"
  call assert_equal('some "XXX" text', getline(1))
  3,4normal .
  call assert_equal('some "XXX" text', getline(3))
  call assert_equal('more "XXX" text', getline(4))
  call Apply()
  call assert_equal('some "XXX" text', getline(5))
  call assert_equal('more "XXX" text', getline(6))
  bwipe!

  nunmap g.
  delfunc Operator
  delfunc Apply
endfunc

func Test_trim()
  call assert_equal("Testing", trim("  \t\r\r\x0BTesting  \t\n\r\n\t\x0B\x0B"))
  call assert_equal("Testing", "  \t  \r\r\n\n\x0BTesting  \t\n\r\n\t\x0B\x0B"->trim())
  call assert_equal("RESERVE", trim("xyz \twwRESERVEzyww \t\t", " wxyz\t"))
  call assert_equal("wRE    \tSERVEzyww", trim("wRE    \tSERVEzyww"))
  call assert_equal("abcd\t     xxxx   tail", trim(" \tabcd\t     xxxx   tail"))
  call assert_equal("\tabcd\t     xxxx   tail", trim(" \tabcd\t     xxxx   tail", " "))
  call assert_equal(" \tabcd\t     xxxx   tail", trim(" \tabcd\t     xxxx   tail", "abx"))
  call assert_equal("RESERVE", trim("你RESERVE好", "你好"))
  call assert_equal("您R E SER V E早", trim("你好您R E SER V E早好你你", "你好"))
  call assert_equal("你好您R E SER V E早好你你", trim(" \n\r\r   你好您R E SER V E早好你你    \t  \x0B", ))
  call assert_equal("您R E SER V E早好你你    \t  \x0B", trim("    你好您R E SER V E早好你你    \t  \x0B", " 你好"))
  call assert_equal("您R E SER V E早好你你    \t  \x0B", trim("    tteesstttt你好您R E SER V E早好你你    \t  \x0B ttestt", " 你好tes"))
  call assert_equal("您R E SER V E早好你你    \t  \x0B", trim("    tteesstttt你好您R E SER V E早好你你    \t  \x0B ttestt", "   你你你好好好tttsses"))
  call assert_equal("留下", trim("这些些不要这些留下这些", "这些不要"))
  call assert_equal("", trim("", ""))
  call assert_equal("a", trim("a", ""))
  call assert_equal("", trim("", "a"))

  call assert_equal("vim", trim("  vim  ", " ", 0))
  call assert_equal("vim  ", trim("  vim  ", " ", 1))
  call assert_equal("  vim", trim("  vim  ", " ", 2))
  call assert_fails('eval trim("  vim  ", " ", [])', 'E745:')
  call assert_fails('eval trim("  vim  ", " ", -1)', 'E475:')
  call assert_fails('eval trim("  vim  ", " ", 3)', 'E475:')
  call assert_fails('eval trim("  vim  ", 0)', 'E1174:')

  let chars = join(map(range(1, 0x20) + [0xa0], {n -> n->nr2char()}), '')
  call assert_equal("x", trim(chars . "x" . chars))

  call assert_fails('let c=trim([])', 'E730:')
endfunc

" Test for reg_recording() and reg_executing()
func Test_reg_executing_and_recording()
  let s:reg_stat = ''
  func s:save_reg_stat()
    let s:reg_stat = reg_recording() . ':' . reg_executing()
    return ''
  endfunc

  new
  call s:save_reg_stat()
  call assert_equal(':', s:reg_stat)
  call feedkeys("qa\"=s:save_reg_stat()\<CR>pq", 'xt')
  call assert_equal('a:', s:reg_stat)
  call feedkeys("@a", 'xt')
  call assert_equal(':a', s:reg_stat)
  call feedkeys("qb@aq", 'xt')
  call assert_equal('b:a', s:reg_stat)
  call feedkeys("q\"\"=s:save_reg_stat()\<CR>pq", 'xt')
  call assert_equal('":', s:reg_stat)

  " :normal command saves and restores reg_executing
  let s:reg_stat = ''
  let @q = ":call TestFunc()\<CR>:call s:save_reg_stat()\<CR>"
  func TestFunc() abort
    normal! ia
  endfunc
  call feedkeys("@q", 'xt')
  call assert_equal(':q', s:reg_stat)
  delfunc TestFunc

  " getchar() command saves and restores reg_executing
  map W :call TestFunc()<CR>
  let @q = "W"
  let g:typed = ''
  let g:regs = []
  func TestFunc() abort
    let g:regs += [reg_executing()]
    let g:typed = getchar(0)
    let g:regs += [reg_executing()]
  endfunc
  call feedkeys("@qy", 'xt')
  call assert_equal(char2nr("y"), g:typed)
  call assert_equal(['q', 'q'], g:regs)
  delfunc TestFunc
  unmap W
  unlet g:typed
  unlet g:regs

  " input() command saves and restores reg_executing
  map W :call TestFunc()<CR>
  let @q = "W"
  let g:typed = ''
  let g:regs = []
  func TestFunc() abort
    let g:regs += [reg_executing()]
    let g:typed = '?'->input()
    let g:regs += [reg_executing()]
  endfunc
  call feedkeys("@qy\<CR>", 'xt')
  call assert_equal("y", g:typed)
  call assert_equal(['q', 'q'], g:regs)
  delfunc TestFunc
  unmap W
  unlet g:typed
  unlet g:regs

  bwipe!
  delfunc s:save_reg_stat
  unlet s:reg_stat
endfunc

func Test_inputsecret()
  map W :call TestFunc()<CR>
  let @q = "W"
  let g:typed1 = ''
  let g:typed2 = ''
  let g:regs = []
  func TestFunc() abort
    let g:typed1 = '?'->inputsecret()
    let g:typed2 = inputsecret('password: ')
  endfunc
  call feedkeys("@qsomething\<CR>else\<CR>", 'xt')
  call assert_equal("something", g:typed1)
  call assert_equal("else", g:typed2)
  delfunc TestFunc
  unmap W
  unlet g:typed1
  unlet g:typed2
endfunc

func Test_getchar()
  call feedkeys('a', '')
  call assert_equal(char2nr('a'), getchar())
  call assert_equal(0, getchar(0))
  call assert_equal(0, getchar(1))

  call feedkeys('a', '')
  call assert_equal('a', getcharstr())
  call assert_equal('', getcharstr(0))
  call assert_equal('', getcharstr(1))

  call feedkeys("\<M-F2>", '')
  call assert_equal("\<M-F2>", getchar(0))
  call assert_equal(0, getchar(0))

  call setline(1, 'xxxx')
  call test_setmouse(1, 3)
  let v:mouse_win = 9
  let v:mouse_winid = 9
  let v:mouse_lnum = 9
  let v:mouse_col = 9
  call feedkeys("\<S-LeftMouse>", '')
  call assert_equal("\<S-LeftMouse>", getchar())
  call assert_equal(1, v:mouse_win)
  call assert_equal(win_getid(1), v:mouse_winid)
  call assert_equal(1, v:mouse_lnum)
  call assert_equal(3, v:mouse_col)
  enew!
endfunc

func Test_libcall_libcallnr()
  CheckFeature libcall

  if has('win32')
    let libc = 'msvcrt.dll'
  elseif has('mac')
    let libc = 'libSystem.B.dylib'
  elseif executable('ldd')
    let libc = matchstr(split(system('ldd ' . GetVimProg())), '/libc\.so\>')
  endif
  if get(l:, 'libc', '') ==# ''
    " On Unix, libc.so can be in various places.
    if has('linux')
      " There is not documented but regarding the 1st argument of glibc's
      " dlopen an empty string and nullptr are equivalent, so using an empty
      " string for the 1st argument of libcall allows to call functions.
      let libc = ''
    elseif has('sun')
      " Set the path to libc.so according to the architecture.
      let test_bits = system('file ' . GetVimProg())
      let test_arch = system('uname -p')
      if test_bits =~ '64-bit' && test_arch =~ 'sparc'
        let libc = '/usr/lib/sparcv9/libc.so'
      elseif test_bits =~ '64-bit' && test_arch =~ 'i386'
        let libc = '/usr/lib/amd64/libc.so'
      else
        let libc = '/usr/lib/libc.so'
      endif
    else
      " Unfortunately skip this test until a good way is found.
      return
    endif
  endif

  if has('win32')
    call assert_equal($USERPROFILE, 'USERPROFILE'->libcall(libc, 'getenv'))
  else
    call assert_equal($HOME, 'HOME'->libcall(libc, 'getenv'))
  endif

  " If function returns NULL, libcall() should return an empty string.
  call assert_equal('', libcall(libc, 'getenv', 'X_ENV_DOES_NOT_EXIT'))

  " Test libcallnr() with string and integer argument.
  call assert_equal(4, 'abcd'->libcallnr(libc, 'strlen'))
  call assert_equal(char2nr('A'), char2nr('a')->libcallnr(libc, 'toupper'))

  call assert_fails("call libcall(libc, 'Xdoesnotexist_', '')", ['', 'E364:'])
  call assert_fails("call libcallnr(libc, 'Xdoesnotexist_', '')", ['', 'E364:'])

  call assert_fails("call libcall('Xdoesnotexist_', 'getenv', 'HOME')", ['', 'E364:'])
  call assert_fails("call libcallnr('Xdoesnotexist_', 'strlen', 'abcd')", ['', 'E364:'])
endfunc

sandbox function Fsandbox()
  normal ix
endfunc

func Test_func_sandbox()
  sandbox let F = {-> 'hello'}
  call assert_equal('hello', F())

  sandbox let F = {-> "normal ix\<Esc>"->execute()}
  call assert_fails('call F()', 'E48:')
  unlet F

  call assert_fails('call Fsandbox()', 'E48:')
  delfunc Fsandbox

  " From a sandbox try to set a predefined variable (which cannot be modified
  " from a sandbox)
  call assert_fails('sandbox let v:lnum = 10', 'E794:')
endfunc

func EditAnotherFile()
  let word = expand('<cword>')
  edit Xfuncrange2
endfunc

func Test_func_range_with_edit()
  " Define a function that edits another buffer, then call it with a range that
  " is invalid in that buffer.
  call writefile(['just one line'], 'Xfuncrange2', 'D')
  new
  eval 10->range()->setline(1)
  write Xfuncrange1
  call assert_fails('5,8call EditAnotherFile()', 'E16:')

  call delete('Xfuncrange1')
  bwipe!
endfunc

func Test_func_exists_on_reload()
  call writefile(['func ExistingFunction()', 'echo "yes"', 'endfunc'], 'Xfuncexists', 'D')
  call assert_equal(0, exists('*ExistingFunction'))
  source Xfuncexists
  call assert_equal(1, '*ExistingFunction'->exists())
  " Redefining a function when reloading a script is OK.
  source Xfuncexists
  call assert_equal(1, exists('*ExistingFunction'))

  " But redefining in another script is not OK.
  call writefile(['func ExistingFunction()', 'echo "yes"', 'endfunc'], 'Xfuncexists2', 'D')
  call assert_fails('source Xfuncexists2', 'E122:')

  " Defining a new function from the cmdline should fail if the function is
  " already defined
  call assert_fails('call feedkeys(":func ExistingFunction()\<CR>", "xt")', 'E122:')

  delfunc ExistingFunction
  call assert_equal(0, exists('*ExistingFunction'))
  call writefile([
	\ 'func ExistingFunction()', 'echo "yes"', 'endfunc',
	\ 'func ExistingFunction()', 'echo "no"', 'endfunc',
	\ ], 'Xfuncexists')
  call assert_fails('source Xfuncexists', 'E122:')
  call assert_equal(1, exists('*ExistingFunction'))

  delfunc ExistingFunction
endfunc

" Test confirm({msg} [, {choices} [, {default} [, {type}]]])
func Test_confirm()
  CheckUnix
  CheckNotGui

  call feedkeys('o', 'L')
  let a = confirm('Press O to proceed')
  call assert_equal(1, a)

  call feedkeys('y', 'L')
  let a = 'Are you sure?'->confirm("&Yes\n&No")
  call assert_equal(1, a)

  call feedkeys('n', 'L')
  let a = confirm('Are you sure?', "&Yes\n&No")
  call assert_equal(2, a)

  " confirm() should return 0 when pressing CTRL-C.
  call feedkeys("\<C-C>", 'L')
  let a = confirm('Are you sure?', "&Yes\n&No")
  call assert_equal(0, a)

  " <Esc> requires another character to avoid it being seen as the start of an
  " escape sequence.  Zero should be harmless.
  eval "\<Esc>0"->feedkeys('L')
  let a = confirm('Are you sure?', "&Yes\n&No")
  call assert_equal(0, a)

  " Default choice is returned when pressing <CR>.
  call feedkeys("\<CR>", 'L')
  let a = confirm('Are you sure?', "&Yes\n&No")
  call assert_equal(1, a)

  call feedkeys("\<CR>", 'L')
  let a = confirm('Are you sure?', "&Yes\n&No", 2)
  call assert_equal(2, a)

  call feedkeys("\<CR>", 'L')
  let a = confirm('Are you sure?', "&Yes\n&No", 0)
  call assert_equal(0, a)

  " Test with the {type} 4th argument
  for type in ['Error', 'Question', 'Info', 'Warning', 'Generic']
    call feedkeys('y', 'L')
    let a = confirm('Are you sure?', "&Yes\n&No\n", 1, type)
    call assert_equal(1, a)
  endfor

  call assert_fails('call confirm([])', 'E730:')
  call assert_fails('call confirm("Are you sure?", [])', 'E730:')
  call assert_fails('call confirm("Are you sure?", "&Yes\n&No\n", [])', 'E745:')
  call assert_fails('call confirm("Are you sure?", "&Yes\n&No\n", 0, [])', 'E730:')
endfunc

func Test_platform_name()
  " The system matches at most only one name.
  let names = ['amiga', 'bsd', 'hpux', 'linux', 'mac', 'qnx', 'sun', 'vms', 'win32', 'win32unix']
  call assert_inrange(0, 1, len(filter(copy(names), 'has(v:val)')))

  " Is Unix?
  call assert_equal(has('bsd'), has('bsd') && has('unix'))
  call assert_equal(has('hpux'), has('hpux') && has('unix'))
  call assert_equal(has('linux'), has('linux') && has('unix'))
  call assert_equal(has('mac'), has('mac') && has('unix'))
  call assert_equal(has('qnx'), has('qnx') && has('unix'))
  call assert_equal(has('sun'), has('sun') && has('unix'))
  call assert_equal(has('win32'), has('win32') && !has('unix'))
  call assert_equal(has('win32unix'), has('win32unix') && has('unix'))

  if has('unix') && executable('uname')
    let uname = system('uname')
    " GNU userland on BSD kernels (e.g., GNU/kFreeBSD) don't have BSD defined
    call assert_equal(uname =~? '\%(GNU/k\w\+\)\@<!BSD\|DragonFly', has('bsd'))
    call assert_equal(uname =~? 'HP-UX', has('hpux'))
    call assert_equal(uname =~? 'Linux', has('linux'))
    call assert_equal(uname =~? 'Darwin', has('mac'))
    call assert_equal(uname =~? 'QNX', has('qnx'))
    call assert_equal(uname =~? 'SunOS', has('sun'))
    call assert_equal(uname =~? 'CYGWIN\|MSYS', has('win32unix'))
  endif
endfunc

func Test_readdir()
  call mkdir('Xreaddir', 'R')
  call writefile([], 'Xreaddir/foo.txt')
  call writefile([], 'Xreaddir/bar.txt')
  call mkdir('Xreaddir/dir')

  " All results
  let files = readdir('Xreaddir')
  call assert_equal(['bar.txt', 'dir', 'foo.txt'], sort(files))

  " Only results containing "f"
  let files = 'Xreaddir'->readdir({ x -> stridx(x, 'f') != -1 })
  call assert_equal(['foo.txt'], sort(files))

  " Only .txt files
  let files = readdir('Xreaddir', { x -> x =~ '.txt$' })
  call assert_equal(['bar.txt', 'foo.txt'], sort(files))

  " Only .txt files with string
  let files = readdir('Xreaddir', 'v:val =~ ".txt$"')
  call assert_equal(['bar.txt', 'foo.txt'], sort(files))

  " Limit to 1 result.
  let l = []
  let files = readdir('Xreaddir', {x -> len(add(l, x)) == 2 ? -1 : 1})
  call assert_equal(1, len(files))

  " Nested readdir() must not crash
  let files = readdir('Xreaddir', 'readdir("Xreaddir", "1") != []')
  call sort(files)->assert_equal(['bar.txt', 'dir', 'foo.txt'])
endfunc

func Test_readdirex()
  call mkdir('Xexdir', 'R')
  call writefile(['foo'], 'Xexdir/foo.txt')
  call writefile(['barbar'], 'Xexdir/bar.txt')
  call mkdir('Xexdir/dir')

  " All results
  let files = readdirex('Xexdir')->map({-> v:val.name})
  call assert_equal(['bar.txt', 'dir', 'foo.txt'], sort(files))
  let sizes = readdirex('Xexdir')->map({-> v:val.size})
  call assert_equal([0, 4, 7], sort(sizes))

  " Only results containing "f"
  let files = 'Xexdir'->readdirex({ e -> stridx(e.name, 'f') != -1 })
			  \ ->map({-> v:val.name})
  call assert_equal(['foo.txt'], sort(files))

  " Only .txt files
  let files = readdirex('Xexdir', { e -> e.name =~ '.txt$' })
			  \ ->map({-> v:val.name})
  call assert_equal(['bar.txt', 'foo.txt'], sort(files))

  " Only .txt files with string
  let files = readdirex('Xexdir', 'v:val.name =~ ".txt$"')
			  \ ->map({-> v:val.name})
  call assert_equal(['bar.txt', 'foo.txt'], sort(files))

  " Limit to 1 result.
  let l = []
  let files = readdirex('Xexdir', {e -> len(add(l, e.name)) == 2 ? -1 : 1})
			  \ ->map({-> v:val.name})
  call assert_equal(1, len(files))

  " Nested readdirex() must not crash
  let files = readdirex('Xexdir', 'readdirex("Xexdir", "1") != []')
			  \ ->map({-> v:val.name})
  call sort(files)->assert_equal(['bar.txt', 'dir', 'foo.txt'])

  " report broken link correctly
  if has("unix")
    call writefile([], 'Xexdir/abc.txt')
    call system("ln -s Xexdir/abc.txt Xexdir/link")
    call delete('Xexdir/abc.txt')
    let files = readdirex('Xexdir', 'readdirex("Xexdir", "1") != []')
			  \ ->map({-> v:val.name .. '_' .. v:val.type})
    call sort(files)->assert_equal(
        \ ['bar.txt_file', 'dir_dir', 'foo.txt_file', 'link_link'])
  endif

  call assert_fails('call readdirex("doesnotexist")', 'E484:')
endfunc

func Test_readdirex_sort()
  CheckUnix
  " Skip tests on Mac OS X and Cygwin (does not allow several files with different casing)
  if has("osxdarwin") || has("osx") || has("macunix") || has("win32unix")
    throw 'Skipped: Test_readdirex_sort on systems that do not allow this using the default filesystem'
  endif
  let _collate = v:collate
  call mkdir('Xsortdir2', 'R')
  call writefile(['1'], 'Xsortdir2/README.txt')
  call writefile(['2'], 'Xsortdir2/Readme.txt')
  call writefile(['3'], 'Xsortdir2/readme.txt')

  " 1) default
  let files = readdirex('Xsortdir2')->map({-> v:val.name})
  let default = copy(files)
  call assert_equal(['README.txt', 'Readme.txt', 'readme.txt'], files, 'sort using default')

  " 2) no sorting
  let files = readdirex('Xsortdir2', 1, #{sort: 'none'})->map({-> v:val.name})
  let unsorted = copy(files)
  call assert_equal(['README.txt', 'Readme.txt', 'readme.txt'], sort(files), 'unsorted')
  call assert_fails("call readdirex('Xsortdir2', 1, #{slort: 'none'})", 'E857: Dictionary key "sort" required')

  " 3) sort by case (same as default)
  let files = readdirex('Xsortdir2', 1, #{sort: 'case'})->map({-> v:val.name})
  call assert_equal(default, files, 'sort by case')

  " 4) sort by ignoring case
  let files = readdirex('Xsortdir2', 1, #{sort: 'icase'})->map({-> v:val.name})
  call assert_equal(unsorted->sort('i'), files, 'sort by icase')

  " 5) Default Collation
  let collate = v:collate
  lang collate C
  let files = readdirex('Xsortdir2', 1, #{sort: 'collate'})->map({-> v:val.name})
  call assert_equal(['README.txt', 'Readme.txt', 'readme.txt'], files, 'sort by C collation')

  " 6) Collation de_DE
  " Switch locale, this may not work on the CI system, if the locale isn't
  " available
  try
    lang collate de_DE
    let files = readdirex('Xsortdir2', 1, #{sort: 'collate'})->map({-> v:val.name})
    call assert_equal(['readme.txt', 'Readme.txt', 'README.txt'], files, 'sort by de_DE collation')
  catch
    throw 'Skipped: de_DE collation is not available'

  finally
    exe 'lang collate' collate
  endtry
endfunc

func Test_readdir_sort()
  " some more cases for testing sorting for readdirex
  let dir = 'Xsortdir3'
  call mkdir(dir, 'R')
  call writefile(['1'], dir .. '/README.txt')
  call writefile(['2'], dir .. '/Readm.txt')
  call writefile(['3'], dir .. '/read.txt')
  call writefile(['4'], dir .. '/Z.txt')
  call writefile(['5'], dir .. '/a.txt')
  call writefile(['6'], dir .. '/b.txt')

  " 1) default
  let files = readdir(dir)
  let default = copy(files)
  call assert_equal(default->sort(), files, 'sort using default')

  " 2) sort by case (same as default)
  let files = readdir(dir, '1', #{sort: 'case'})
  call assert_equal(default, files, 'sort using default')

  " 3) sort by ignoring case
  let files = readdir(dir, '1', #{sort: 'icase'})
  call assert_equal(default->sort('i'), files, 'sort by ignoring case')

  " 4) collation
  let collate = v:collate
  lang collate C
  let files = readdir(dir, 1, #{sort: 'collate'})
  call assert_equal(default->sort(), files, 'sort by C collation')
  exe "lang collate" collate

  " 5) Errors
  call assert_fails('call readdir(dir, 1, 1)', 'E1206:')
  call assert_fails('call readdir(dir, 1, #{sorta: 1})')
  call assert_fails('call readdir(dir, 1, test_null_dict())', 'E1297:')
  call assert_fails('call readdirex(dir, 1, 1)', 'E1206:')
  call assert_fails('call readdirex(dir, 1, #{sorta: 1})')
  call assert_fails('call readdirex(dir, 1, test_null_dict())', 'E1297:')

  " 6) ignore other values in dict
  let files = readdir(dir, '1', #{sort: 'c'})
  call assert_equal(default, files, 'sort using default2')

  " Cleanup
  exe "lang collate" collate
endfunc

func Test_delete_rf()
  call mkdir('Xrfdir')
  call writefile([], 'Xrfdir/foo.txt')
  call writefile([], 'Xrfdir/bar.txt')
  call mkdir('Xrfdir/[a-1]')  " issue #696
  call writefile([], 'Xrfdir/[a-1]/foo.txt')
  call writefile([], 'Xrfdir/[a-1]/bar.txt')
  call assert_true(filereadable('Xrfdir/foo.txt'))
  call assert_true('Xrfdir/[a-1]/foo.txt'->filereadable())

  call assert_equal(0, delete('Xrfdir', 'rf'))
  call assert_false(filereadable('Xrfdir/foo.txt'))
  call assert_false(filereadable('Xrfdir/[a-1]/foo.txt'))

  if has('unix')
    call mkdir('Xrfdir/Xdir2', 'p')
    silent !chmod 555 Xrfdir
    call assert_equal(-1, delete('Xrfdir/Xdir2', 'rf'))
    call assert_equal(-1, delete('Xrfdir', 'rf'))
    silent !chmod 755 Xrfdir
    call assert_equal(0, delete('Xrfdir', 'rf'))
  endif
endfunc

func Test_call()
  call assert_equal(3, call('len', [123]))
  call assert_equal(3, 'len'->call([123]))
  call assert_fails("call call('len', 123)", 'E1211:')
  call assert_equal(0, call('', []))
  call assert_equal(0, call('len', test_null_list()))

  function Mylen() dict
     return len(self.data)
  endfunction
  let mydict = {'data': [0, 1, 2, 3], 'len': function("Mylen")}
  eval mydict.len->call([], mydict)->assert_equal(4)
  call assert_fails("call call('Mylen', [], 0)", 'E1206:')
  call assert_fails('call foo', 'E107:')

  " These once caused a crash.
  call call(test_null_function(), [])
  call call(test_null_partial(), [])
  call assert_fails('call test_null_function()()', 'E1192:')
  call assert_fails('call test_null_partial()()', 'E117:')

  let lines =<< trim END
      let Time = 'localtime'
      call Time()
  END
  call v9.CheckScriptFailure(lines, 'E1085:')
endfunc

func Test_char2nr()
  call assert_equal(12354, char2nr('あ', 1))
  call assert_equal(120, 'x'->char2nr())
  set encoding=latin1
  call assert_equal(120, 'x'->char2nr())
  set encoding=utf-8
endfunc

func Test_charclass()
  call assert_equal(0, charclass(' '))
  call assert_equal(1, charclass('.'))
  call assert_equal(2, charclass('x'))
  call assert_equal(3, charclass("\u203c"))
  " this used to crash vim
  call assert_equal(0, "xxx"[-1]->charclass())
endfunc

func Test_eventhandler()
  call assert_equal(0, eventhandler())
endfunc

func Test_bufadd_bufload()
  call assert_equal(0, bufexists('someName'))
  let buf = bufadd('someName')
  call assert_notequal(0, buf)
  call assert_equal(1, bufexists('someName'))
  call assert_equal(0, getbufvar(buf, '&buflisted'))
  call assert_equal(0, bufloaded(buf))
  call bufload(buf)
  call assert_equal(1, bufloaded(buf))
  call assert_equal([''], getbufline(buf, 1, '$'))

  let curbuf = bufnr('')
  eval ['some', 'text']->writefile('XotherName')
  let buf = 'XotherName'->bufadd()
  call assert_notequal(0, buf)
  eval 'XotherName'->bufexists()->assert_equal(1)
  call assert_equal(0, getbufvar(buf, '&buflisted'))
  call assert_equal(0, bufloaded(buf))
  eval buf->bufload()
  call assert_equal(1, bufloaded(buf))
  call assert_equal(['some', 'text'], getbufline(buf, 1, '$'))
  call assert_equal(curbuf, bufnr(''))

  let buf1 = bufadd('')
  let buf2 = bufadd('')
  call assert_notequal(0, buf1)
  call assert_notequal(0, buf2)
  call assert_notequal(buf1, buf2)
  call assert_equal(1, bufexists(buf1))
  call assert_equal(1, bufexists(buf2))
  call assert_equal(0, bufloaded(buf1))
  exe 'bwipe ' .. buf1
  call assert_equal(0, bufexists(buf1))
  call assert_equal(1, bufexists(buf2))
  exe 'bwipe ' .. buf2
  call assert_equal(0, bufexists(buf2))

  " When 'buftype' is "nofile" then bufload() does not read the file.
  " Other values too.
  for val in [['nofile', 0],
            \ ['nowrite', 1],
            \ ['acwrite', 1],
            \ ['quickfix', 0],
            \ ['help', 1],
            \ ['terminal', 0],
            \ ['prompt', 0],
            \ ['popup', 0],
            \ ]
    bwipe! XotherName
    let buf = bufadd('XotherName')
    call setbufvar(buf, '&bt', val[0])
    call bufload(buf)
    call assert_equal(val[1] ? ['some', 'text'] : [''], getbufline(buf, 1, '$'), val[0])
  endfor

  bwipe someName
  bwipe XotherName
  call assert_equal(0, bufexists('someName'))
  call delete('XotherName')
endfunc

func Test_state()
  CheckRunVimInTerminal

  let getstate = ":echo 'state: ' .. g:state .. '; mode: ' .. g:mode\<CR>"

  let lines =<< trim END
	call setline(1, ['one', 'two', 'three'])
	map ;; gg
	set complete=.
	func RunTimer()
	  call timer_start(10, {id -> execute('let g:state = state()') .. execute('let g:mode = mode()')})
	endfunc
	au Filetype foobar let g:state = state()|let g:mode = mode()
  END
  call writefile(lines, 'XState')
  let buf = RunVimInTerminal('-S XState', #{rows: 6})

  " Using a ":" command Vim is busy, thus "S" is returned
  call term_sendkeys(buf, ":echo 'state: ' .. state() .. '; mode: ' .. mode()\<CR>")
  call WaitForAssert({-> assert_match('state: S; mode: n', term_getline(buf, 6))}, 1000)
  call term_sendkeys(buf, ":\<CR>")

  " Using a timer callback
  call term_sendkeys(buf, ":call RunTimer()\<CR>")
  call TermWait(buf, 25)
  call term_sendkeys(buf, getstate)
  call WaitForAssert({-> assert_match('state: c; mode: n', term_getline(buf, 6))}, 1000)

  " Halfway a mapping
  call term_sendkeys(buf, ":call RunTimer()\<CR>;")
  call TermWait(buf, 25)
  call term_sendkeys(buf, ";")
  call term_sendkeys(buf, getstate)
  call WaitForAssert({-> assert_match('state: mSc; mode: n', term_getline(buf, 6))}, 1000)

  " Insert mode completion (bit slower on Mac)
  call term_sendkeys(buf, ":call RunTimer()\<CR>Got\<C-N>")
  call TermWait(buf, 25)
  call term_sendkeys(buf, "\<Esc>")
  call term_sendkeys(buf, getstate)
  call WaitForAssert({-> assert_match('state: aSc; mode: i', term_getline(buf, 6))}, 1000)

  " Autocommand executing
  call term_sendkeys(buf, ":set filetype=foobar\<CR>")
  call TermWait(buf, 25)
  call term_sendkeys(buf, getstate)
  call WaitForAssert({-> assert_match('state: xS; mode: n', term_getline(buf, 6))}, 1000)

  " Todo: "w" - waiting for ch_evalexpr()

  " messages scrolled
  call term_sendkeys(buf, ":call RunTimer()\<CR>:echo \"one\\ntwo\\nthree\"\<CR>")
  call TermWait(buf, 25)
  call term_sendkeys(buf, "\<CR>")
  call term_sendkeys(buf, getstate)
  call WaitForAssert({-> assert_match('state: Scs; mode: r', term_getline(buf, 6))}, 1000)

  call StopVimInTerminal(buf)
  call delete('XState')
endfunc

func Test_range()
  " destructuring
  let [x, y] = range(2)
  call assert_equal([0, 1], [x, y])

  " index
  call assert_equal(4, range(1, 10)[3])

  " add()
  call assert_equal([0, 1, 2, 3], add(range(3), 3))
  call assert_equal([0, 1, 2, [0, 1, 2]], add([0, 1, 2], range(3)))
  call assert_equal([0, 1, 2, [0, 1, 2]], add(range(3), range(3)))

  " append()
  new
  call append('.', range(5))
  call assert_equal(['', '0', '1', '2', '3', '4'], getline(1, '$'))
  bwipe!

  " appendbufline()
  new
  call appendbufline(bufnr(''), '.', range(5))
  call assert_equal(['0', '1', '2', '3', '4', ''], getline(1, '$'))
  bwipe!

  " call()
  func TwoArgs(a, b)
    return [a:a, a:b]
  endfunc
  call assert_equal([0, 1], call('TwoArgs', range(2)))

  " col()
  new
  call setline(1, ['foo', 'bar'])
  call assert_equal(2, col(range(1, 2)))
  bwipe!

  " complete()
  execute "normal! a\<C-r>=[complete(col('.'), range(10)), ''][1]\<CR>"
  " complete_info()
  execute "normal! a\<C-r>=[complete(col('.'), range(10)), ''][1]\<CR>\<C-r>=[complete_info(range(5)), ''][1]\<CR>"

  " copy()
  call assert_equal([1, 2, 3], copy(range(1, 3)))

  " count()
  call assert_equal(0, count(range(0), 3))
  call assert_equal(0, count(range(2), 3))
  call assert_equal(1, count(range(5), 3))

  " cursor()
  new
  call setline(1, ['aaa', 'bbb', 'ccc'])
  call cursor(range(1, 2))
  call assert_equal([2, 1], [col('.'), line('.')])
  bwipe!

  " deepcopy()
  call assert_equal([1, 2, 3], deepcopy(range(1, 3)))

  " empty()
  call assert_true(empty(range(0)))
  call assert_false(empty(range(2)))

  " execute()
  new
  call setline(1, ['aaa', 'bbb', 'ccc'])
  call execute(range(3))
  call assert_equal(2, line('.'))
  bwipe!

  " extend()
  call assert_equal([1, 2, 3, 4], extend([1], range(2, 4)))
  call assert_equal([1, 2, 3, 4], extend(range(1, 1), range(2, 4)))
  call assert_equal([1, 2, 3, 4], extend(range(1, 1), [2, 3, 4]))

  " filter()
  call assert_equal([1, 3], filter(range(5), 'v:val % 2'))
  call assert_equal([1, 5, 7, 11, 13], filter(filter(range(15), 'v:val % 2'), 'v:val % 3'))

  " funcref()
  call assert_equal([0, 1], funcref('TwoArgs', range(2))())

  " function()
  call assert_equal([0, 1], function('TwoArgs', range(2))())

  " garbagecollect()
  let thelist = [1, range(2), 3]
  let otherlist = range(3)
  call test_garbagecollect_now()

  " get()
  call assert_equal(4, get(range(1, 10), 3))
  call assert_equal(-1, get(range(1, 10), 42, -1))

  " index()
  call assert_equal(1, index(range(1, 5), 2))
  call assert_fails("echo index([1, 2], 1, [])", 'E745:')

  " insert()
  call assert_equal([42, 1, 2, 3, 4, 5], insert(range(1, 5), 42))
  call assert_equal([42, 1, 2, 3, 4, 5], insert(range(1, 5), 42, 0))
  call assert_equal([1, 42, 2, 3, 4, 5], insert(range(1, 5), 42, 1))
  call assert_equal([1, 2, 3, 4, 42, 5], insert(range(1, 5), 42, 4))
  call assert_equal([1, 2, 3, 4, 42, 5], insert(range(1, 5), 42, -1))
  call assert_equal([1, 2, 3, 4, 5, 42], insert(range(1, 5), 42, 5))

  " join()
  call assert_equal('0 1 2 3 4', join(range(5)))

  " json_encode()
  call assert_equal('[0,1,2,3]', json_encode(range(4)))

  " len()
  call assert_equal(0, len(range(0)))
  call assert_equal(2, len(range(2)))
  call assert_equal(5, len(range(0, 12, 3)))
  call assert_equal(4, len(range(3, 0, -1)))

  " list2str()
  call assert_equal('ABC', list2str(range(65, 67)))
  call assert_fails('let s = list2str(5)', 'E1211:')

  " lock()
  let thelist = range(5)
  lockvar thelist

  " map()
  call assert_equal([0, 2, 4, 6, 8], map(range(5), 'v:val * 2'))
  call assert_equal([3, 5, 7, 9, 11], map(map(range(5), 'v:val * 2'), 'v:val + 3'))
  call assert_equal([2, 6], map(filter(range(5), 'v:val % 2'), 'v:val * 2'))
  call assert_equal([2, 4, 8], filter(map(range(5), 'v:val * 2'), 'v:val % 3'))

  " match()
  call assert_equal(3, match(range(5), 3))

  " matchaddpos()
  highlight MyGreenGroup ctermbg=green guibg=green
  call matchaddpos('MyGreenGroup', range(line('.'), line('.')))

  " matchend()
  call assert_equal(4, matchend(range(5), '4'))
  call assert_equal(3, matchend(range(1, 5), '4'))
  call assert_equal(-1, matchend(range(1, 5), '42'))

  " matchstrpos()
  call assert_equal(['4', 4, 0, 1], matchstrpos(range(5), '4'))
  call assert_equal(['4', 3, 0, 1], matchstrpos(range(1, 5), '4'))
  call assert_equal(['', -1, -1, -1], matchstrpos(range(1, 5), '42'))

  " max() reverse()
  call assert_equal(0, max(range(0)))
  call assert_equal(0, max(range(10, 9)))
  call assert_equal(9, max(range(10)))
  call assert_equal(18, max(range(0, 20, 3)))
  call assert_equal(20, max(range(20, 0, -3)))
  call assert_equal(99999, max(range(100000)))
  call assert_equal(99999, max(range(99999, 0, -1)))
  call assert_equal(99999, max(reverse(range(100000))))
  call assert_equal(99999, max(reverse(range(99999, 0, -1))))

  " min() reverse()
  call assert_equal(0, min(range(0)))
  call assert_equal(0, min(range(10, 9)))
  call assert_equal(5, min(range(5, 10)))
  call assert_equal(5, min(range(5, 10, 3)))
  call assert_equal(2, min(range(20, 0, -3)))
  call assert_equal(0, min(range(100000)))
  call assert_equal(0, min(range(99999, 0, -1)))
  call assert_equal(0, min(reverse(range(100000))))
  call assert_equal(0, min(reverse(range(99999, 0, -1))))

  " remove()
  call assert_equal(1, remove(range(1, 10), 0))
  call assert_equal(2, remove(range(1, 10), 1))
  call assert_equal(9, remove(range(1, 10), 8))
  call assert_equal(10, remove(range(1, 10), 9))
  call assert_equal(10, remove(range(1, 10), -1))
  call assert_equal([3, 4, 5], remove(range(1, 10), 2, 4))

  " repeat()
  call assert_equal([0, 1, 2, 0, 1, 2], repeat(range(3), 2))
  call assert_equal([0, 1, 2], repeat(range(3), 1))
  call assert_equal([], repeat(range(3), 0))
  call assert_equal([], repeat(range(5, 4), 2))
  call assert_equal([], repeat(range(5, 4), 0))

  " reverse()
  call assert_equal([2, 1, 0], reverse(range(3)))
  call assert_equal([0, 1, 2, 3], reverse(range(3, 0, -1)))
  call assert_equal([9, 8, 7, 6, 5, 4, 3, 2, 1, 0], reverse(range(10)))
  call assert_equal([20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10], reverse(range(10, 20)))
  call assert_equal([16, 13, 10], reverse(range(10, 18, 3)))
  call assert_equal([19, 16, 13, 10], reverse(range(10, 19, 3)))
  call assert_equal([19, 16, 13, 10], reverse(range(10, 20, 3)))
  call assert_equal([11, 14, 17, 20], reverse(range(20, 10, -3)))
  call assert_equal([], reverse(range(0)))

  " TODO: setpos()
  " new
  " call setline(1, repeat([''], bufnr('')))
  " call setline(bufnr('') + 1, repeat('x', bufnr('') * 2 + 6))
  " call setpos('x', range(bufnr(''), bufnr('') + 3))
  " bwipe!

  " setreg()
  call setreg('a', range(3))
  call assert_equal("0\n1\n2\n", getreg('a'))

  " settagstack()
  call settagstack(1, #{items : range(4)})

  " sign_define()
  call assert_fails("call sign_define(range(5))", "E715:")
  call assert_fails("call sign_placelist(range(5))", "E715:")

  " sign_undefine()
  call assert_fails("call sign_undefine(range(5))", "E908:")

  " sign_unplacelist()
  call assert_fails("call sign_unplacelist(range(5))", "E715:")

  " sort()
  call assert_equal([0, 1, 2, 3, 4, 5], sort(range(5, 0, -1)))

  " string()
  call assert_equal('[0, 1, 2, 3, 4]', string(range(5)))

  " taglist() with 'tagfunc'
  func TagFunc(pattern, flags, info)
    return range(10)
  endfunc
  set tagfunc=TagFunc
  call assert_fails("call taglist('asdf')", 'E987:')
  set tagfunc=

  " term_start()
  if has('terminal') && has('termguicolors')
    call assert_fails('call term_start(range(3, 4))', 'E474:')
    let g:terminal_ansi_colors = range(16)
    if has('win32')
      let cmd = "cmd /c dir"
    else
      let cmd = "ls"
    endif
    call assert_fails('call term_start("' .. cmd .. '", #{term_finish: "close"'
        \ .. ', ansi_colors: range(16)})', 'E475:')
    unlet g:terminal_ansi_colors
  endif

  " type()
  call assert_equal(v:t_list, type(range(5)))

  " uniq()
  call assert_equal([0, 1, 2, 3, 4], uniq(range(5)))

  " errors
  call assert_fails('let x=range(2, 8, 0)', 'E726:')
  call assert_fails('let x=range(3, 1)', 'E727:')
  call assert_fails('let x=range(1, 3, -2)', 'E727:')
  call assert_fails('let x=range([])', 'E745:')
  call assert_fails('let x=range(1, [])', 'E745:')
  call assert_fails('let x=range(1, 4, [])', 'E745:')
endfunc

func Test_garbagecollect_now_fails()
  let v:testing = 0
  call assert_fails('call test_garbagecollect_now()', 'E1142:')
  let v:testing = 1
endfunc

func Test_echoraw()
  CheckScreendump

  " Normally used for escape codes, but let's test with a CR.
  let lines =<< trim END
    call echoraw("hello\<CR>x")
  END
  call writefile(lines, 'XTest_echoraw')
  let buf = RunVimInTerminal('-S XTest_echoraw', {'rows': 5, 'cols': 40})
  call VerifyScreenDump(buf, 'Test_functions_echoraw', {})

  " clean up
  call StopVimInTerminal(buf)
  call delete('XTest_echoraw')
endfunc

" Test for echo highlighting
func Test_echohl()
  echohl Search
  echo 'Vim'
  call assert_equal('Vim', Screenline(&lines))
  " TODO: How to check the highlight group used by echohl?
  " ScreenAttrs() returns all zeros.
  echohl None
endfunc

" Test for the eval() function
func Test_eval()
  call assert_fails("call eval('5 a')", 'E488:')
endfunc

" Test for the keytrans() function
func Test_keytrans()
  call assert_equal('<Space>', keytrans(' '))
  call assert_equal('<lt>', keytrans('<'))
  call assert_equal('<lt>Tab>', keytrans('<Tab>'))
  call assert_equal('<Tab>', keytrans("\<Tab>"))
  call assert_equal('<C-V>', keytrans("\<C-V>"))
  call assert_equal('<BS>', keytrans("\<BS>"))
  call assert_equal('<Home>', keytrans("\<Home>"))
  call assert_equal('<C-Home>', keytrans("\<C-Home>"))
  call assert_equal('<M-Home>', keytrans("\<M-Home>"))
  call assert_equal('<C-Space>', keytrans("\<C-Space>"))
  call assert_equal('<M-Space>', keytrans("\<*M-Space>"))
  call assert_equal('<M-x>', "\<*M-x>"->keytrans())
  call assert_equal('<C-I>', "\<*C-I>"->keytrans())
  call assert_equal('<S-3>', "\<*S-3>"->keytrans())
  call assert_equal('π', 'π'->keytrans())
  call assert_equal('<M-π>', "\<M-π>"->keytrans())
  call assert_equal('ě', 'ě'->keytrans())
  call assert_equal('<M-ě>', "\<M-ě>"->keytrans())
  call assert_equal('', ''->keytrans())
  call assert_equal('', test_null_string()->keytrans())
  call assert_fails('call keytrans(1)', 'E1174:')
  call assert_fails('call keytrans()', 'E119:')
endfunc

" Test for the nr2char() function
func Test_nr2char()
  set encoding=latin1
  call assert_equal('@', nr2char(64))
  set encoding=utf8
  call assert_equal('a', nr2char(97, 1))
  call assert_equal('a', nr2char(97, 0))

  call assert_equal("\x80\xfc\b" .. nr2char(0x100000), eval('"\<M-' .. nr2char(0x100000) .. '>"'))
  call assert_equal("\x80\xfc\b" .. nr2char(0x40000000), eval('"\<M-' .. nr2char(0x40000000) .. '>"'))
endfunc

" Test for screenattr(), screenchar() and screenchars() functions
func Test_screen_functions()
  call assert_equal(-1, screenattr(-1, -1))
  call assert_equal(-1, screenchar(-1, -1))
  call assert_equal([], screenchars(-1, -1))

  " Run this in a separate Vim instance to avoid messing up.
  let after =<< trim [CODE]
    scriptencoding utf-8
    call setline(1, '口')
    redraw
    call assert_equal(0, screenattr(1, 1))
    call assert_equal(char2nr('口'), screenchar(1, 1))
    call assert_equal([char2nr('口')], screenchars(1, 1))
    call assert_equal('口', screenstring(1, 1))
    call writefile(v:errors, 'Xresult')
    qall!
  [CODE]

  let encodings = ['utf-8', 'cp932', 'cp936', 'cp949', 'cp950']
  if !has('win32')
    let encodings += ['euc-jp']
  endif
  for enc in encodings
    let msg = 'enc=' .. enc
    if RunVim([], after, $'--clean --cmd "set encoding={enc}"')
      call assert_equal([], readfile('Xresult'), msg)
    endif
    call delete('Xresult')
  endfor
endfunc

" Test for getcurpos() and setpos()
func Test_getcurpos_setpos()
  new
  call setline(1, ['012345678', '012345678'])
  normal gg6l
  let sp = getcurpos()
  normal 0
  call setpos('.', sp)
  normal jyl
  call assert_equal('6', @")
  call assert_equal(-1, setpos('.', test_null_list()))
  call assert_equal(-1, setpos('.', {}))

  let winid = win_getid()
  normal G$
  let pos = getcurpos()
  wincmd w
  call assert_equal(pos, getcurpos(winid))

  wincmd w
  close!

  call assert_equal(getcurpos(), getcurpos(0))
  call assert_equal([0, 0, 0, 0, 0], getcurpos(-1))
  call assert_equal([0, 0, 0, 0, 0], getcurpos(1999))
endfunc

func Test_getmousepos()
  enew!
  call setline(1, "\t\t\t1234")
  call test_setmouse(1, 1)
  call assert_equal(#{
        \ screenrow: 1,
        \ screencol: 1,
        \ winid: win_getid(),
        \ winrow: 1,
        \ wincol: 1,
        \ line: 1,
        \ column: 1,
        \ }, getmousepos())
  call test_setmouse(1, 25)
  call assert_equal(#{
        \ screenrow: 1,
        \ screencol: 25,
        \ winid: win_getid(),
        \ winrow: 1,
        \ wincol: 25,
        \ line: 1,
        \ column: 4,
        \ }, getmousepos())
  call test_setmouse(1, 50)
  call assert_equal(#{
        \ screenrow: 1,
        \ screencol: 50,
        \ winid: win_getid(),
        \ winrow: 1,
        \ wincol: 50,
        \ line: 1,
        \ column: 8,
        \ }, getmousepos())

  " If the mouse is positioned past the last buffer line, "line" and "column"
  " should act like it's positioned on the last buffer line.
  call test_setmouse(2, 25)
  call assert_equal(#{
        \ screenrow: 2,
        \ screencol: 25,
        \ winid: win_getid(),
        \ winrow: 2,
        \ wincol: 25,
        \ line: 1,
        \ column: 4,
        \ }, getmousepos())
  call test_setmouse(2, 50)
  call assert_equal(#{
        \ screenrow: 2,
        \ screencol: 50,
        \ winid: win_getid(),
        \ winrow: 2,
        \ wincol: 50,
        \ line: 1,
        \ column: 8,
        \ }, getmousepos())
  bwipe!
endfunc

func Test_getmouseshape()
  CheckFeature mouseshape

  call assert_equal('arrow', getmouseshape())
endfunc

" Test for glob()
func Test_glob()
  call assert_equal('', glob(test_null_string()))
  call assert_equal('', globpath(test_null_string(), test_null_string()))
  call assert_fails("let x = globpath(&rtp, 'syntax/c.vim', [])", 'E745:')

  call writefile([], 'Xglob1')
  call writefile([], 'XGLOB2')
  set wildignorecase
  " Sort output of glob() otherwise we end up with different
  " ordering depending on whether file system is case-sensitive.
  call assert_equal(['XGLOB2', 'Xglob1'], sort(glob('Xglob[12]', 0, 1)))
  " wildignorecase shall be applied even when the pattern contains no wildcards.
  call assert_equal('XGLOB2', glob('xglob2'))
  set wildignorecase&

  call delete('Xglob1')
  call delete('XGLOB2')

  call assert_fails("call glob('*', 0, {})", 'E728:')
endfunc

" Test for browse()
func Test_browse()
  CheckFeature browse
  call assert_fails('call browse([], "open", "x", "a.c")', 'E745:')
endfunc

" Test for browsedir()
func Test_browsedir()
  CheckFeature browse
  call assert_fails('call browsedir("open", [])', 'E730:')
endfunc

func HasDefault(msg = 'msg')
  return a:msg
endfunc

func Test_default_arg_value()
  call assert_equal('msg', HasDefault())
endfunc

" Test for gettext()
func Test_gettext()
  call assert_fails('call gettext(1)', 'E1174:')
endfunc

func Test_builtin_check()
  call assert_fails('let g:["trim"] = {x -> " " .. x}', 'E704:')
  call assert_fails('let g:.trim = {x -> " " .. x}', 'E704:')
  call assert_fails('let l:["trim"] = {x -> " " .. x}', 'E704:')
  call assert_fails('let l:.trim = {x -> " " .. x}', 'E704:')
  let lines =<< trim END
    vim9script
    var trim = (x) => " " .. x
  END
  call v9.CheckScriptFailure(lines, 'E704:')

  call assert_fails('call extend(g:, #{foo: { -> "foo" }})', 'E704:')
  let g:bar = 123
  call extend(g:, #{bar: { -> "foo" }}, "keep")
  call assert_fails('call extend(g:, #{bar: { -> "foo" }}, "force")', 'E704:')
  unlet g:bar

  call assert_fails('call extend(l:, #{foo: { -> "foo" }})', 'E704:')
  let bar = 123
  call extend(l:, #{bar: { -> "foo" }}, "keep")
  call assert_fails('call extend(l:, #{bar: { -> "foo" }}, "force")', 'E704:')
  unlet bar

  call assert_fails('call extend(g:, #{foo: function("extend")})', 'E704:')
  let g:bar = 123
  call extend(g:, #{bar: function("extend")}, "keep")
  call assert_fails('call extend(g:, #{bar: function("extend")}, "force")', 'E704:')
  unlet g:bar

  call assert_fails('call extend(l:, #{foo: function("extend")})', 'E704:')
  let bar = 123
  call extend(l:, #{bar: function("extend")}, "keep")
  call assert_fails('call extend(l:, #{bar: function("extend")}, "force")', 'E704:')
  unlet bar
endfunc

func Test_funcref_to_string()
  let Fn = funcref('g:Test_funcref_to_string')
  call assert_equal("function('g:Test_funcref_to_string')", string(Fn))
endfunc

" Test for isabsolutepath()
func Test_isabsolutepath()
  call assert_false(isabsolutepath(''))
  call assert_false(isabsolutepath('.'))
  call assert_false(isabsolutepath('../Foo'))
  call assert_false(isabsolutepath('Foo/'))
  if has('win32')
    call assert_true(isabsolutepath('A:\'))
    call assert_true(isabsolutepath('A:\Foo'))
    call assert_true(isabsolutepath('A:/Foo'))
    call assert_false(isabsolutepath('A:Foo'))
    call assert_false(isabsolutepath('\Windows'))
    call assert_true(isabsolutepath('\\Server2\Share\Test\Foo.txt'))
  else
    call assert_true(isabsolutepath('/'))
    call assert_true(isabsolutepath('/usr/share/'))
  endif
endfunc

" Test for exepath()
func Test_exepath()
  if has('win32')
    call assert_notequal(exepath('cmd'), '')

    let oldNoDefaultCurrentDirectoryInExePath = $NoDefaultCurrentDirectoryInExePath
    call writefile(['@echo off', 'echo Evil'], 'vim-test-evil.bat')
    let $NoDefaultCurrentDirectoryInExePath = ''
    call assert_notequal(exepath("vim-test-evil.bat"), '')
    let $NoDefaultCurrentDirectoryInExePath = '1'
    call assert_equal(exepath("vim-test-evil.bat"), '')
    let $NoDefaultCurrentDirectoryInExePath = oldNoDefaultCurrentDirectoryInExePath
    call delete('vim-test-evil.bat')
  else
    call assert_notequal(exepath('sh'), '')
  endif
endfunc

" Test for virtcol()
func Test_virtcol()
  enew!
  call setline(1, "the\tquick\tbrown\tfox")
  norm! 4|
  call assert_equal(8, virtcol('.'))
  call assert_equal(8, virtcol('.', v:false))
  call assert_equal([4, 8], virtcol('.', v:true))
  bwipe!
endfunc

func Test_delfunc_while_listing()
  CheckRunVimInTerminal

  let lines =<< trim END
      set nocompatible
      for i in range(1, 999)
        exe 'func ' .. 'MyFunc' .. i .. '()'
        endfunc
      endfor
      au CmdlineLeave : call timer_start(0, {-> execute('delfunc MyFunc622')})
  END
  call writefile(lines, 'Xfunctionclear', 'D')
  let buf = RunVimInTerminal('-S Xfunctionclear', {'rows': 12})

  " This was using freed memory.  The height of the terminal must be so that
  " the next function to be listed with "j" is the one that is deleted in the
  " timer callback, tricky!
  call term_sendkeys(buf, ":func /MyFunc\<CR>")
  call TermWait(buf, 50)
  call term_sendkeys(buf, "j")
  call TermWait(buf, 50)
  call term_sendkeys(buf, "\<CR>")

  call StopVimInTerminal(buf)
endfunc

" Test for the reverse() function with a string
func Test_string_reverse()
  let lines =<< trim END
    call assert_equal('', reverse(test_null_string()))
    for [s1, s2] in [['', ''], ['a', 'a'], ['ab', 'ba'], ['abc', 'cba'],
                   \ ['abcd', 'dcba'], ['«-«-»-»', '»-»-«-«'],
                   \ ['🇦', '🇦'], ['🇦🇧', '🇧🇦'], ['🇦🇧🇨', '🇨🇧🇦'],
                   \ ['🇦«🇧-🇨»🇩', '🇩»🇨-🇧«🇦']]
      call assert_equal(s2, reverse(s1))
    endfor
  END
  call v9.CheckLegacyAndVim9Success(lines)

  " test in latin1 encoding
  let save_enc = &encoding
  set encoding=latin1
  call assert_equal('dcba', reverse('abcd'))
  let &encoding = save_enc
endfunc

" vim: shiftwidth=2 sts=2 expandtab