patch 9.1.1110: Vim tests are slow and flaky

Problem:  Vim tests are slow and flaky at the same time due to reliance
          on timeouts which are unreliable.
Solution: improve Vim test performance and reduce flakiness
          (Yee Cheng Chin)

A lot of Vim tests currently rely on waiting a specific amount of time
before asserting a condition. This is bad because 1) it is slow, as the
timeout is hardcoded, 2) it's unreliable as a resource-starved runner
may overshoot the timeout. Also, there are a lot of builtin sleep
commands in commonly used utilities like VerifyScreenDump and WaitFor()
which leads to a lot of unnecessary idle time.

Fix these issues by doing the following:
1. Make utilities like VerifyScreenDump and WaitFor use the lowest wait
   time possible (1 ms). This essentially turns it into a spin wait. On
   fast machines, these will finish very quickly. For existing tests
   that had an implicit reliance on the old timeouts (e.g.
   VerifyScreenDump had a 50ms wait before), fix the tests to wait that
   specific amount explicitly.
2. Fix tests that sleep or wait for long amounts of time to instead
   explicitly use a callback mechanism to be notified when a child
   terminal job has finished. This allows the test to only take as much
   time as possible instead of having to hard code an unreliable
   timeout.

With these fixes, tests should 1) completely quickly on fast machines,
and 2) on slow machines they will still run to completion albeit slowly.
Note that previoulsy both were not true. The hardcoded timeouts meant
that on fast machines the tests were mostly idling wasting time, whereas
on slow machines, the timeouts often were not generous enough to allow
them to run to completion.

closes: #16615

Signed-off-by: Yee Cheng Chin <ychin.git@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_crash.vim b/src/testdir/test_crash.vim
index c83ddf2..85b1290 100644
--- a/src/testdir/test_crash.vim
+++ b/src/testdir/test_crash.vim
@@ -4,11 +4,15 @@
 
 CheckScreendump
 
+" Run the command in terminal and wait for it to complete via notification
+func s:RunCommandAndWait(buf, cmd)
+  call term_sendkeys(a:buf, a:cmd .. "; printf '" .. TermNotifyParentCmd(v:false) .. "'\<cr>")
+  call WaitForChildNotification()
+endfunc
+
 func Test_crash1()
   CheckNotBSD
   CheckExecutable dash
-  " Test 7 fails on Mac ...
-  CheckNotMac
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -19,70 +23,59 @@
   let file = 'crash/poc_huaf1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > X_crash1_result.txt')
 
   let file = 'crash/poc_huaf2'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/poc_huaf3'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 100)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/bt_quickfix_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 4: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('Xerr')
-  " This test takes a bit longer
-  call TermWait(buf, 1000)
 
   let file = 'crash/poc_tagfunc.vim'
   let args = printf(cmn_args, vim, file)
   " using || because this poc causes vim to exit with exitstatus != 0
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 5: [OK]" >> X_crash1_result.txt')
 
-  call TermWait(buf, 100)
 
   let file = 'crash/bt_quickfix1_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 6: [OK]" >> X_crash1_result.txt')
   " clean up
   call delete('X')
-  call TermWait(buf, 3000)
 
   let file = 'crash/vim_regsub_both_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 7: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/vim_msg_trunc_poc'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 3000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/crash_scrollbar'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt')
 
   let file = 'crash/editing_arg_idx_POC_1'
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt' .. "\<cr>")
-  call TermWait(buf, 1000)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  || echo "crash 10: [OK]" >> X_crash1_result.txt')
   call delete('Xerr')
   call delete('@')
 
@@ -113,7 +106,6 @@
 func Test_crash1_2()
   CheckNotBSD
   CheckExecutable dash
-  let g:test_is_flaky = 1
 
   " The following used to crash Vim
   let opts = #{cmd: 'sh'}
@@ -125,37 +117,32 @@
   let file = 'crash/poc1'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 1: [OK]" > '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 1: [OK]" > '.. result)
 
   let file = 'crash/poc_win_enter_ext'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 2: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 350)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 2: [OK]" >> '.. result)
 
   let file = 'crash/poc_suggest_trie_walk'
   let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ '  && echo "crash 3: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ '  && echo "crash 3: [OK]" >> '.. result)
 
   let file = 'crash/poc_did_set_langmap'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 4: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 4: [OK]" >> '.. result)
 
   let file = 'crash/reverse_text_overflow'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args ..
-    \ ' ; echo "crash 5: [OK]" >> '.. result .. "\<cr>")
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args ..
+    \ ' ; echo "crash 5: [OK]" >> '.. result)
 
   " clean up
   exe buf .. "bw!"
@@ -181,64 +168,49 @@
   let buf = RunVimInTerminal('sh', #{cmd: 'sh'})
 
   let file = 'crash/poc_ex_substitute'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/poc_uaf_exec_instructions'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/poc_uaf_check_argument_types'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/double_free'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/dialog_changed_uaf'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/nullpointer'
-  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'\<cr>"
+  let cmn_args = "%s -u NONE -i NONE -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/heap_overflow3'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/heap_overflow_glob2regpat'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
+  call s:RunCommandAndWait(buf, args)
 
   let file = 'crash/nullptr_regexp_nfa'
   let cmn_args = "%s -u NONE -i NONE -n -X -m -n -e -s -S %s -c ':qa!'"
   let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 50)
-
-  let file = 'crash/ex_redraw_crash'
-  let cmn_args = "%s -u NONE -i NONE -n -m -X -Z -e -s -S %s -c ':qa!'"
-  let args = printf(cmn_args, vim, file)
-  call term_sendkeys(buf, args)
-  call TermWait(buf, 150)
+  call s:RunCommandAndWait(buf, args)
 
   " clean up
   exe buf .. "bw!"