Comment .less code correctly

spec/app/language-mode-spec.coffee

@@ -12,7 +12,7 @@ describe "LanguageMode", ->
     beforeEach ->
       atom.activatePackage('javascript-tmbundle', sync: true)
       editSession = project.open('sample.js', autoIndent: false)
-      { buffer, languageMode } = editSession
+      {buffer, languageMode} = editSession
 
     describe ".toggleLineCommentsForBufferRows(start, end)", ->
       it "comments/uncomments lines in the given range", ->
@@ -54,7 +54,7 @@ describe "LanguageMode", ->
     beforeEach ->
       atom.activatePackage('coffee-script-tmbundle', sync: true)
       editSession = project.open('coffee.coffee', autoIndent: false)
-      { buffer, languageMode } = editSession
+      {buffer, languageMode} = editSession
 
     describe ".toggleLineCommentsForBufferRows(start, end)", ->
       it "comments/uncomments lines in the given range", ->
@@ -90,7 +90,7 @@ describe "LanguageMode", ->
     beforeEach ->
       atom.activatePackage('css-tmbundle', sync: true)
       editSession = project.open('css.css', autoIndent: false)
-      { buffer, languageMode } = editSession
+      {buffer, languageMode} = editSession
 
     describe ".toggleLineCommentsForBufferRows(start, end)", ->
       it "comments/uncomments lines in the given range", ->
@@ -126,3 +126,16 @@ describe "LanguageMode", ->
         buffer.change([[2, 0], [2, Infinity]], "   /*width: 110%;*/ ")
         languageMode.toggleLineCommentsForBufferRows(2, 2)
         expect(buffer.lineForRow(2)).toBe "   width: 110%; "
+
+  describe "less", ->
+    beforeEach ->
+      atom.activatePackage('less-tmbundle', sync: true)
+      atom.activatePackage('css-tmbundle', sync: true)
+      editSession = project.open('sample.less', autoIndent: false)
+      {buffer, languageMode} = editSession
+
+    describe "when commenting lines", ->
+      it "only uses the `commentEnd` pattern if it comes from the same grammar as the `commentStart`", ->
+        languageMode.toggleLineCommentsForBufferRows(0, 0)
+        expect(buffer.lineForRow(0)).toBe "// @color: #4D926F;"
+

src/app/language-mode.coffee

@@ -37,14 +37,20 @@ class LanguageMode
   # Returns an {Array} of the commented {Ranges}.
   toggleLineCommentsForBufferRows: (start, end) ->
     scopes = @editSession.scopesForBufferPosition([start, 0])
-    return unless commentStartString = syntax.getProperty(scopes, "editor.commentStart")
+    properties = syntax.propertiesForScope(scopes, "editor.commentStart")[0]
+    return unless properties
+
+    commentStartString = _.valueForKeyPath(properties, "editor.commentStart")
+    commentEndString = _.valueForKeyPath(properties, "editor.commentEnd")
+
+    return unless commentStartString
 
     buffer = @editSession.buffer
     commentStartRegexString = _.escapeRegExp(commentStartString).replace(/(\s+)$/, '($1)?')
     commentStartRegex = new OnigRegExp("^(\\s*)(#{commentStartRegexString})")
     shouldUncomment = commentStartRegex.test(buffer.lineForRow(start))
 
-    if commentEndString = syntax.getProperty(scopes, "editor.commentEnd")
+    if commentEndString
       if shouldUncomment
         commentEndRegexString = _.escapeRegExp(commentEndString).replace(/^(\s+)/, '($1)?')
         commentEndRegex = new OnigRegExp("(#{commentEndRegexString})(\\s*)$")