patch 9.0.0849: terminal mouse test is a bit flaky

Problem:    Terminal mouse test is a bit flaky.
Solution:   Add WaitFor() calls. (James McCoy closes #11519)  Tune wait times
            to reduce flakiness.

src/testdir/test_terminal3.vim

@@ -267,11 +267,11 @@ func Test_terminal_in_popup()
 	\ ]
   call writefile(lines, 'XtermPopup', 'D')
   let buf = RunVimInTerminal('-S XtermPopup', #{rows: 15})
-  call TermWait(buf, 100)
+  call TermWait(buf, 200)
   call term_sendkeys(buf, ":call OpenTerm(0)\<CR>")
-  call TermWait(buf, 500)
+  call TermWait(buf, 800)
   call term_sendkeys(buf, ":\<CR>")
-  call TermWait(buf, 100)
+  call TermWait(buf, 500)
   call term_sendkeys(buf, "\<C-W>:echo getwinvar(g:winid, \"&buftype\") win_gettype(g:winid)\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_1', {})
 
@@ -279,9 +279,9 @@ func Test_terminal_in_popup()
   call VerifyScreenDump(buf, 'Test_terminal_popup_2', {})
  
   call term_sendkeys(buf, ":call OpenTerm(1)\<CR>")
-  call TermWait(buf, 500)
+  call TermWait(buf, 800)
   call term_sendkeys(buf, ":set hlsearch\<CR>")
-  call TermWait(buf, 100)
+  call TermWait(buf, 500)
   call term_sendkeys(buf, "/edit\<CR>")
   call VerifyScreenDump(buf, 'Test_terminal_popup_3', {})
  
@@ -686,6 +686,8 @@ func Test_term_mouse()
   call TermWait(buf)
   redraw!
 
+  let XbufExists = {-> filereadable('Xbuf')}
+
   " Use the mouse to enter the terminal window
   call win_gotoid(prev_win)
   call feedkeys(MouseLeftClickCode(1, 1), 'x')
@@ -698,73 +700,76 @@ func Test_term_mouse()
   call test_setmouse(3, 8)
   call term_sendkeys(buf, "\<LeftMouse>\<LeftRelease>")
   call TermWait(buf, 50)
+  call delete('Xbuf')
   call term_sendkeys(buf, ":call writefile([json_encode(getpos('.'))], 'Xbuf')\<CR>")
   call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   let pos = json_decode(readfile('Xbuf')[0])
   call assert_equal([3, 8], pos[1:2])
+  call delete('Xbuf')
 
   " Test for selecting text using mouse
-  call delete('Xbuf')
   call test_setmouse(2, 11)
   call term_sendkeys(buf, "\<LeftMouse>")
   call test_setmouse(2, 16)
   call term_sendkeys(buf, "\<LeftRelease>y")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([@\"], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal('yellow', readfile('Xbuf')[0])
+  call delete('Xbuf')
 
   " Test for selecting text using double click
-  call delete('Xbuf')
   call test_setmouse(1, 11)
   call term_sendkeys(buf, "\<LeftMouse>\<LeftRelease>\<LeftMouse>")
   call test_setmouse(1, 17)
   call term_sendkeys(buf, "\<LeftRelease>y")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([@\"], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal('three four', readfile('Xbuf')[0])
+  call delete('Xbuf')
 
   " Test for selecting a line using triple click
-  call delete('Xbuf')
   call test_setmouse(3, 2)
   call term_sendkeys(buf, "\<LeftMouse>\<LeftRelease>\<LeftMouse>\<LeftRelease>\<LeftMouse>\<LeftRelease>y")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([@\"], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal("vim emacs sublime nano\n", readfile('Xbuf')[0])
+  call delete('Xbuf')
 
   " Test for selecting a block using quadruple click
-  call delete('Xbuf')
   call test_setmouse(1, 11)
   call term_sendkeys(buf, "\<LeftMouse>\<LeftRelease>\<LeftMouse>\<LeftRelease>\<LeftMouse>\<LeftRelease>\<LeftMouse>")
   call test_setmouse(3, 13)
   call term_sendkeys(buf, "\<LeftRelease>y")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([@\"], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal("ree\nyel\nsub", readfile('Xbuf')[0])
+  call delete('Xbuf')
 
   " Test for extending a selection using right click
-  call delete('Xbuf')
   call test_setmouse(2, 9)
   call term_sendkeys(buf, "\<LeftMouse>\<LeftRelease>")
   call test_setmouse(2, 16)
   call term_sendkeys(buf, "\<RightMouse>\<RightRelease>y")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([@\"], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal("n yellow", readfile('Xbuf')[0])
+  call delete('Xbuf')
 
   " Test for pasting text using middle click
-  call delete('Xbuf')
   call term_sendkeys(buf, ":let @r='bright '\<CR>")
   call test_setmouse(2, 22)
   call term_sendkeys(buf, "\"r\<MiddleMouse>\<MiddleRelease>")
   call TermWait(buf, 50)
   call term_sendkeys(buf, ":call writefile([getline(2)], 'Xbuf')\<CR>")
-  call TermWait(buf, 50)
+  call WaitFor(XbufExists)
   call assert_equal("red bright blue", readfile('Xbuf')[0][-15:])
+  call delete('Xbuf')
 
   " cleanup
   call TermWait(buf)

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    849,
 /**/
     848,
 /**/