patch 9.1.0351: No test that completing a partial mapping clears 'showcmd'

Problem:  No test that completing a partial mapping clears 'showcmd'.
Solution: Complete partial mappings in Test_showcmd_part_map() instead
          of using :echo.  Adjust some comments (zeertzjq).

closes: #14580

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_mapping.vim b/src/testdir/test_mapping.vim
index 309be71..c98d5bf 100644
--- a/src/testdir/test_mapping.vim
+++ b/src/testdir/test_mapping.vim
@@ -1811,7 +1811,7 @@
 func Test_showcmd_part_map()
   CheckRunVimInTerminal
 
-  let lines =<< trim eval END
+  let lines =<< trim END
     set notimeout showcmd
     nnoremap ,a <Ignore>
     nnoremap ;a <Ignore>
@@ -1831,20 +1831,21 @@
   for c in [',', ';', 'À', 'Ë', 'β', 'ω', '…']
     call term_sendkeys(buf, c)
     call WaitForAssert({-> assert_equal(c, trim(term_getline(buf, 6)))})
-    call term_sendkeys(buf, "\<C-C>:echo\<CR>")
-    call WaitForAssert({-> assert_equal('', term_getline(buf, 6))})
+    call term_sendkeys(buf, 'a')
+    call WaitForAssert({-> assert_equal('', trim(term_getline(buf, 6)))})
   endfor
 
   call term_sendkeys(buf, "\<C-W>")
   call WaitForAssert({-> assert_equal('^W', trim(term_getline(buf, 6)))})
-  call term_sendkeys(buf, "\<C-C>:echo\<CR>")
-  call WaitForAssert({-> assert_equal('', term_getline(buf, 6))})
+  call term_sendkeys(buf, 'a')
+  call WaitForAssert({-> assert_equal('', trim(term_getline(buf, 6)))})
 
-  " Use feedkeys() as terminal buffer cannot forward this
+  " Use feedkeys() as terminal buffer cannot forward unsimplified Ctrl-W.
+  " This is like typing Ctrl-W with modifyOtherKeys enabled.
   call term_sendkeys(buf, ':call feedkeys("\<*C-W>", "m")' .. " | echo\<CR>")
   call WaitForAssert({-> assert_equal('^W', trim(term_getline(buf, 6)))})
-  call term_sendkeys(buf, "\<C-C>:echo\<CR>")
-  call WaitForAssert({-> assert_equal('', term_getline(buf, 6))})
+  call term_sendkeys(buf, 'a')
+  call WaitForAssert({-> assert_equal('', trim(term_getline(buf, 6)))})
 
   call StopVimInTerminal(buf)
 endfunc
diff --git a/src/testdir/test_utf8.vim b/src/testdir/test_utf8.vim
index 3fd83cf..0f46240 100644
--- a/src/testdir/test_utf8.vim
+++ b/src/testdir/test_utf8.vim
@@ -300,7 +300,7 @@
   call StopVimInTerminal(buf)
 endfunc
 
-" When `setcellwidth` is used on characters that are not targets of `ambiwidth`.
+" Test setcellwidths() on characters that are not targets of 'ambiwidth'.
 func Test_setcellwidths_with_non_ambiwidth_character_dump()
   CheckRunVimInTerminal
 
@@ -321,7 +321,6 @@
   call StopVimInTerminal(buf)
 endfunc
 
-
 " For some reason this test causes Test_customlist_completion() to fail on CI,
 " so run it as the last test.
 func Test_zz_ambiwidth_hl_dump()