vim-patch:9.1.0990: Inconsistent behavior when changing cmdheight (#31830)

Problem:  Inconsistent behavior when changing cmdheight by resizing the
          topframe through wincmds and dragging laststatus. Changing
          cmdheight by resizing the topframe does not trigger OptionSet.
Solution: Consolidate logic for changing the cmdheight, set the option
          value to handle side-effects (Luuk van Baal)

e15cbc1af4

vim-patch:9.0.0187: command line height changes when maximizing window height

Problem:  Command line height changes when maximizing window height.
Solution: Do not change the command line height. (closes vim/vim#10885)

96bde99bf8

test/old/testdir/test_autocmd.vim

@@ -4181,4 +4181,28 @@ func Test_autocmd_BufWinLeave_with_vsp()
   exe "bw! " .. dummy
 endfunc
 
+func Test_OptionSet_cmdheight()
+  set mouse=a laststatus=2
+  au OptionSet cmdheight :let &l:ch = v:option_new
+
+  resize -1
+  call assert_equal(2, &l:ch)
+  resize +1
+  call assert_equal(1, &l:ch)
+
+  call Ntest_setmouse(&lines - 1, 1)
+  call feedkeys("\<LeftMouse>", 'xt')
+  call Ntest_setmouse(&lines - 2, 1)
+  call feedkeys("\<LeftDrag>", 'xt')
+  call assert_equal(2, &l:ch)
+
+  tabnew | resize +1
+  call assert_equal(1, &l:ch)
+  tabfirst
+  call assert_equal(2, &l:ch)
+
+  tabonly
+  set cmdheight& mouse& laststatus&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

test/old/testdir/test_cmdline.vim

@@ -291,9 +291,10 @@ func Test_changing_cmdheight()
   call term_sendkeys(buf, ":resize -3\<CR>")
   call VerifyScreenDump(buf, 'Test_changing_cmdheight_1', {})
 
-  " using the space available doesn't change the status line
-  call term_sendkeys(buf, ":set cmdheight+=3\<CR>")
+  " :resize now also changes 'cmdheight' accordingly
+  call term_sendkeys(buf, ":set cmdheight+=1\<CR>")
   call VerifyScreenDump(buf, 'Test_changing_cmdheight_2', {})
+  call term_sendkeys(buf, ":set cmdheight-=1\<CR>")
 
   " using more space moves the status line up
   call term_sendkeys(buf, ":set cmdheight+=1\<CR>")
@@ -312,7 +313,7 @@ func Test_changing_cmdheight()
   call term_sendkeys(buf, ":call EchoTwo()\<CR>")
   call VerifyScreenDump(buf, 'Test_changing_cmdheight_6', {})
 
-  " increasing 'cmdheight' doesn't clear the messages that need hit-enter
+  " decreasing 'cmdheight' doesn't clear the messages that need hit-enter
   call term_sendkeys(buf, ":call EchoOne()\<CR>")
   call VerifyScreenDump(buf, 'Test_changing_cmdheight_7', {})
 

test/old/testdir/test_window_cmd.vim

@@ -56,7 +56,6 @@ func Test_window_cmd_cmdwin_with_vsp()
 endfunc
 
 func Test_cmdheight_not_changed()
-  throw 'Skipped: N/A'
   set cmdheight=2
   set winminheight=0
   augroup Maximize