patch 9.0.2102: matchparen highlight not cleared in completion mode

Problem:  matchparen highlight not cleared in completion mode
Solution: Clear matchparen highlighting in completion mode

Remove hard-coded hack in insexpand.c to clear the :3match before
displaying the completion menu.

Add a test for matchparen highlighting. While at it, move all test tests
related to the matchparen plugin into a separate test file.

closes: #13493
closes: #13524

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/testdir/test_matchparen.vim

@@ -0,0 +1,87 @@
+" Test for the matchparen plugin
+
+if !has('gui_running') && has('unix')
+  set term=ansi
+endif
+
+source view_util.vim
+source check.vim
+source screendump.vim
+
+" Test for scrolling that modifies buffer during visual block
+func Test_visual_block_scroll()
+  CheckScreendump
+
+  let lines =<< trim END
+    source $VIMRUNTIME/plugin/matchparen.vim
+    set scrolloff=1
+    call setline(1, ['a', 'b', 'c', 'd', 'e', '', '{', '}', '{', 'f', 'g', '}'])
+    call cursor(5, 1)
+  END
+
+  let filename = 'Xvisualblockmodifiedscroll'
+  call writefile(lines, filename, 'D')
+
+  let buf = RunVimInTerminal('-S '.filename, #{rows: 7})
+  call term_sendkeys(buf, "V\<C-D>\<C-D>")
+
+  call VerifyScreenDump(buf, 'Test_display_visual_block_scroll', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+" Test for clearing paren highlight when switching buffers
+func Test_matchparen_clear_highlight()
+  CheckScreendump
+
+  let lines =<< trim END
+    source $VIMRUNTIME/plugin/matchparen.vim
+    set hidden
+    call setline(1, ['()'])
+    normal 0
+
+    func OtherBuffer()
+       enew
+       exe "normal iaa\<Esc>0"
+    endfunc
+  END
+  call writefile(lines, 'XMatchparenClear', 'D')
+  let buf = RunVimInTerminal('-S XMatchparenClear', #{rows: 5})
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_1', {})
+
+  call term_sendkeys(buf, ":call OtherBuffer()\<CR>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_2', {})
+
+  call term_sendkeys(buf, "\<C-^>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_1', {})
+
+  call term_sendkeys(buf, "\<C-^>:\<Esc>")
+  call VerifyScreenDump(buf, 'Test_matchparen_clear_highlight_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+" Test for scrolling that modifies buffer during visual block
+func Test_matchparen_pum_clear()
+  CheckScreendump
+
+  let lines =<< trim END
+    source $VIMRUNTIME/plugin/matchparen.vim
+    set completeopt=menuone
+    call setline(1, ['aa', 'aaa', 'aaaa', '(a)'])
+    call cursor(4, 3)
+  END
+
+  let filename = 'Xmatchparen'
+  call writefile(lines, filename, 'D')
+
+  let buf = RunVimInTerminal('-S '.filename, #{rows: 10})
+  call term_sendkeys(buf, "i\<C-N>\<C-N>")
+
+  call VerifyScreenDump(buf, 'Test_matchparen_pum_clear_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+
+" vim: shiftwidth=2 sts=2 expandtab