From b1a4db0b69e4744f9a4b4e4844021bb9026f03a6 Mon Sep 17 00:00:00 2001
From: nate <nateozemon@gmail.com>
Date: Thu, 9 Nov 2017 13:33:37 -0800
Subject: [PATCH 1/2] :highlight : avoid redraw on error

do_highlight() should not redraw if a validation error occurred.
closes #7489
---
 src/nvim/syntax.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index d28e996581..bc7362af72 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -6648,7 +6648,7 @@ do_highlight(char_u *line, int forceit, int init) {
   if (error && idx == highlight_ga.ga_len) {
     syn_unadd_group();
   } else {
-    if (is_normal_group) {
+    if (!error && is_normal_group) {
       // Need to update all groups, because they might be using "bg" and/or
       // "fg", which have been changed now.
       highlight_attr_set_all();

From ebed8c6a2eb641397bd7a7b34ea46ca5c02ea346 Mon Sep 17 00:00:00 2001
From: nate <nateozemon@gmail.com>
Date: Fri, 24 Nov 2017 09:03:06 -0800
Subject: [PATCH 2/2] test: :highlight validation errors

add test when highlight group doesn't exist.
add test when an invalid color name is used for `cterm`.
---
 test/functional/ex_cmds/highlight_spec.lua | 43 ++++++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 test/functional/ex_cmds/highlight_spec.lua

diff --git a/test/functional/ex_cmds/highlight_spec.lua b/test/functional/ex_cmds/highlight_spec.lua
new file mode 100644
index 0000000000..25968b8204
--- /dev/null
+++ b/test/functional/ex_cmds/highlight_spec.lua
@@ -0,0 +1,43 @@
+local Screen = require('test.functional.ui.screen')
+local helpers = require("test.functional.helpers")(after_each)
+local eq, command = helpers.eq, helpers.command
+local clear = helpers.clear
+local eval, exc_exec = helpers.eval, helpers.exc_exec
+
+describe(':highlight', function()
+  local screen
+
+  before_each(function()
+    clear()
+    screen = Screen.new()
+    screen:attach()
+  end)
+
+  after_each(function()
+    screen:detach()
+  end)
+
+  it('invalid color name', function()
+    eq('Vim(highlight):E421: Color name or number not recognized: ctermfg=#181818',
+       exc_exec("highlight normal ctermfg=#181818"))
+    eq('Vim(highlight):E421: Color name or number not recognized: ctermbg=#181818',
+       exc_exec("highlight normal ctermbg=#181818"))
+  end)
+
+  it('invalid group name', function()
+    eq('Vim(highlight):E411: highlight group not found: foo',
+       exc_exec("highlight foo"))
+  end)
+
+  it('"Normal" foreground with red', function()
+    eq('', eval('synIDattr(hlID("Normal"), "fg", "cterm")'))
+    command('highlight normal ctermfg=red')
+    eq('9', eval('synIDattr(hlID("Normal"), "fg", "cterm")'))
+  end)
+
+  it('"Normal" background with red', function()
+    eq('', eval('synIDattr(hlID("Normal"), "bg", "cterm")'))
+    command('highlight normal ctermbg=red')
+    eq('9', eval('synIDattr(hlID("Normal"), "bg", "cterm")'))
+  end)
+end)