fix(comment): fall back to using trimmed comment markers (#28938)

Problem: Currently comment detection, addition, and removal are done
  by matching 'commentstring' exactly. This has the downside when users
  want to add comment markers with space (like with `-- %s`
  commentstring) but also be able to uncomment lines that do not contain
  space (like `--aaa`).

Solution: Use the following approach:
  - Line is commented if it matches 'commentstring' with trimmed parts.
  - Adding comment is 100% relying on 'commentstring' parts (as is now).
  - Removing comment is first trying exact 'commentstring' parts with
    fallback on trying its trimmed parts.

1 files changed, 23 insertions, 16 deletions

diff --git a/test/functional/lua/comment_spec.lua b/test/functional/lua/comment_spec.lua
index 9b1d9613cb..bbf061a2ab 100644
--- a/test/functional/lua/comment_spec.lua
+++ b/test/functional/lua/comment_spec.lua
@@ -301,27 +301,34 @@ describe('commenting', function()
       eq(get_lines(), { 'aa', '', '  ', '\t', 'aa' })
     end)
 
-    it('matches comment parts strictly when detecting comment/uncomment', function()
+    it('correctly matches comment parts during checking and uncommenting', function()
       local validate = function(from, to, ref_lines)
-        set_lines({ '#aa', '# aa', '#  aa' })
+        set_lines({ '/*aa*/', '/* aa */', '/*  aa  */' })
         toggle_lines(from, to)
         eq(get_lines(), ref_lines)
       end
 
-      set_commentstring('#%s')
-      validate(1, 3, { 'aa', ' aa', '  aa' })
-      validate(2, 3, { '#aa', ' aa', '  aa' })
-      validate(3, 3, { '#aa', '# aa', '  aa' })
-
-      set_commentstring('# %s')
-      validate(1, 3, { '# #aa', '# # aa', '# #  aa' })
-      validate(2, 3, { '#aa', 'aa', ' aa' })
-      validate(3, 3, { '#aa', '# aa', ' aa' })
-
-      set_commentstring('#  %s')
-      validate(1, 3, { '#  #aa', '#  # aa', '#  #  aa' })
-      validate(2, 3, { '#aa', '#  # aa', '#  #  aa' })
-      validate(3, 3, { '#aa', '# aa', 'aa' })
+      -- Should first try to match 'commentstring' parts exactly with their
+      -- whitespace, with fallback on trimmed parts
+      set_commentstring('/*%s*/')
+      validate(1, 3, { 'aa', ' aa ', '  aa  ' })
+      validate(2, 3, { '/*aa*/', ' aa ', '  aa  ' })
+      validate(3, 3, { '/*aa*/', '/* aa */', '  aa  ' })
+
+      set_commentstring('/* %s */')
+      validate(1, 3, { 'aa', 'aa', ' aa ' })
+      validate(2, 3, { '/*aa*/', 'aa', ' aa ' })
+      validate(3, 3, { '/*aa*/', '/* aa */', ' aa ' })
+
+      set_commentstring('/*  %s  */')
+      validate(1, 3, { 'aa', ' aa ', 'aa' })
+      validate(2, 3, { '/*aa*/', ' aa ', 'aa' })
+      validate(3, 3, { '/*aa*/', '/* aa */', 'aa' })
+
+      set_commentstring(' /*%s*/ ')
+      validate(1, 3, { 'aa', ' aa ', '  aa  ' })
+      validate(2, 3, { '/*aa*/', ' aa ', '  aa  ' })
+      validate(3, 3, { '/*aa*/', '/* aa */', '  aa  ' })
     end)
 
     it('uncomments on inconsistent indent levels', function()