patch 8.1.1581: shared functions for testing are disorganised

Problem:    Shared functions for testing are disorganised.
Solution:   Group finctions in script files. (Ozaki Kiichi, closes #4573)

src/testdir/term_util.vim

@@ -0,0 +1,106 @@
+" Functions about terminal shared by several tests
+
+" Only load this script once.
+if exists('*CanRunVimInTerminal')
+  finish
+endif
+
+" For most tests we need to be able to run terminal Vim with 256 colors.  On
+" MS-Windows the console only has 16 colors and the GUI can't run in a
+" terminal.
+func CanRunVimInTerminal()
+  return has('terminal') && !has('win32')
+endfunc
+
+" Skip the rest if there is no terminal feature at all.
+if !has('terminal')
+  finish
+endif
+
+" Stops the shell running in terminal "buf".
+func StopShellInTerminal(buf)
+  call term_sendkeys(a:buf, "exit\r")
+  let job = term_getjob(a:buf)
+  call WaitFor({-> job_status(job) == "dead"})
+endfunc
+
+" Run Vim with "arguments" in a new terminal window.
+" By default uses a size of 20 lines and 75 columns.
+" Returns the buffer number of the terminal.
+"
+" Options is a dictionary, these items are recognized:
+" "rows" - height of the terminal window (max. 20)
+" "cols" - width of the terminal window (max. 78)
+" "statusoff" - number of lines the status is offset from default
+func RunVimInTerminal(arguments, options)
+  " If Vim doesn't exit a swap file remains, causing other tests to fail.
+  " Remove it here.
+  call delete(".swp")
+
+  if exists('$COLORFGBG')
+    " Clear $COLORFGBG to avoid 'background' being set to "dark", which will
+    " only be corrected if the response to t_RB is received, which may be too
+    " late.
+    let $COLORFGBG = ''
+  endif
+
+  " Make a horizontal and vertical split, so that we can get exactly the right
+  " size terminal window.  Works only when the current window is full width.
+  call assert_equal(&columns, winwidth(0))
+  split
+  vsplit
+
+  " Always do this with 256 colors and a light background.
+  set t_Co=256 background=light
+  hi Normal ctermfg=NONE ctermbg=NONE
+
+  " Make the window 20 lines high and 75 columns, unless told otherwise.
+  let rows = get(a:options, 'rows', 20)
+  let cols = get(a:options, 'cols', 75)
+  let statusoff = get(a:options, 'statusoff', 1)
+
+  let cmd = GetVimCommandClean()
+
+  " Add -v to have gvim run in the terminal (if possible)
+  let cmd .= ' -v ' . a:arguments
+  let buf = term_start(cmd, {
+	\ 'curwin': 1,
+	\ 'term_rows': rows,
+	\ 'term_cols': cols,
+	\ })
+  if &termwinsize == ''
+    " in the GUI we may end up with a different size, try to set it.
+    if term_getsize(buf) != [rows, cols]
+      call term_setsize(buf, rows, cols)
+    endif
+    call assert_equal([rows, cols], term_getsize(buf))
+  else
+    let rows = term_getsize(buf)[0]
+    let cols = term_getsize(buf)[1]
+  endif
+
+  " Wait for "All" or "Top" of the ruler to be shown in the last line or in
+  " the status line of the last window. This can be quite slow (e.g. when
+  " using valgrind).
+  " If it fails then show the terminal contents for debugging.
+  try
+    call WaitFor({-> len(term_getline(buf, rows)) >= cols - 1 || len(term_getline(buf, rows - statusoff)) >= cols - 1})
+  catch /timed out after/
+    let lines = map(range(1, rows), {key, val -> term_getline(buf, val)})
+    call assert_report('RunVimInTerminal() failed, screen contents: ' . join(lines, "<NL>"))
+  endtry
+
+  return buf
+endfunc
+
+" Stop a Vim running in terminal buffer "buf".
+func StopVimInTerminal(buf)
+  call assert_equal("running", term_getstatus(a:buf))
+
+  " CTRL-O : works both in Normal mode and Insert mode to start a command line.
+  " In Command-line it's inserted, the CTRL-U removes it again.
+  call term_sendkeys(a:buf, "\<C-O>:\<C-U>qa!\<cr>")
+
+  call WaitForAssert({-> assert_equal("finished", term_getstatus(a:buf))})
+  only!
+endfunc