src/testdir/test_channel.vim

" Test for channel functions.
scriptencoding utf-8

" This requires the Python command to run the test server.
" This most likely only works on Unix and Windows console.
if has('unix')
  " We also need the pkill command to make sure the server can be stopped.
  if !executable('python') || !executable('pkill')
    finish
  endif
elseif has('win32') && !has('gui_win32')
  " Use Python Launcher for Windows (py.exe).
  if !executable('py')
    finish
  endif
else
  finish
endif

func s:start_server()
  if has('win32')
    silent !start cmd /c start "test_channel" py test_channel.py
  else
    silent !python test_channel.py&
  endif
endfunc

func s:kill_server()
  if has('win32')
    call system('taskkill /IM py.exe /T /F /FI "WINDOWTITLE eq test_channel"')
  else
    call system("pkill --full test_channel.py")
  endif
endfunc

func Test_communicate()
  call delete("Xportnr")
  " The Python program writes the port number in Xportnr.
  call s:start_server()

  " Wait for up to 2 seconds for the port number to be there.
  let cnt = 20
  let l = []
  while cnt > 0
    try
      let l = readfile("Xportnr")
    catch
    endtry
    if len(l) >= 1
      break
    endif
    sleep 100m
    let cnt -= 1
  endwhile
  call delete("Xportnr")

  if len(l) == 0
    " Can't make the connection, give up.
    call s:kill_server()
    return
  endif
  let port = l[0]
  let handle = ch_open('localhost:' . port, 'json')

  " Simple string request and reply.
  call assert_equal('got it', ch_sendexpr(handle, 'hello!'))

  " Request that triggers sending two ex commands.  These will usually be
  " handled before getting the response, but it's not guaranteed, thus wait a
  " tiny bit for the commands to get executed.
  call assert_equal('ok', ch_sendexpr(handle, 'make change'))
  sleep 10m
  call assert_equal('added1', getline(line('$') - 1))
  call assert_equal('added2', getline('$'))

  " make the server quit, can't check if this works, should not hang.
  call ch_sendexpr(handle, '!quit!', 0)

  call s:kill_server()
endfunc