LanguageMode switches to a better-matching grammar when it is added

spec/app/edit-session-spec.coffee

@@ -2060,18 +2060,18 @@ describe "EditSession", ->
       editSession.buffer.reload()
       expect(editSession.getCursorScreenPosition()).toEqual [0,1]
 
-  describe "when the 'grammars-loaded' event is triggered on the syntax global", ->
-    it "reloads the edit session's grammar and re-tokenizes the buffer if it changes", ->
+  describe "when a better-matched grammar is added to syntax", ->
+    it "switches to the better-matched grammar and re-tokenizes the buffer", ->
       editSession.destroy()
       jsGrammar = syntax.selectGrammar('a.js')
-      grammarToReturn = syntax.nullGrammar
-      spyOn(syntax, 'selectGrammar').andCallFake -> grammarToReturn
+      syntax.removeGrammar(jsGrammar)
 
       editSession = project.buildEditSession('sample.js', autoIndent: false)
+      expect(editSession.getGrammar()).toBe syntax.nullGrammar
       expect(editSession.lineForScreenRow(0).tokens.length).toBe 1
 
-      grammarToReturn = jsGrammar
-      syntax.trigger 'grammars-loaded'
+      syntax.addGrammar(jsGrammar)
+      expect(editSession.getGrammar()).toBe jsGrammar
       expect(editSession.lineForScreenRow(0).tokens.length).toBeGreaterThan 1
 
   describe "auto-indent", ->

src/app/language-mode.coffee

@@ -9,15 +9,19 @@ class LanguageMode
   buffer = null
   grammar = null
   editSession = null
+  currentGrammarScore: null
 
   constructor: (@editSession) ->
     @buffer = @editSession.buffer
     @reloadGrammar()
-    syntax.on 'grammars-loaded', => @reloadGrammar()
+    syntax.on 'grammar-added', (grammar) =>
+      newScore = grammar.getScore(@buffer.getPath(), @buffer.getText())
+      @setGrammar(grammar, newScore) if newScore > @currentGrammarScore
 
-  setGrammar: (grammar) ->
+  setGrammar: (grammar, score) ->
     return if grammar is @grammar
     @grammar = grammar
+    @currentGrammarScore = score ? grammar.getScore(@buffer.getPath(), @buffer.getText())
     @trigger 'grammar-changed', grammar
 
   reloadGrammar: ->

src/app/syntax.coffee

@@ -29,6 +29,7 @@ class Syntax
   addGrammar: (grammar) ->
     @grammars.push(grammar)
     @grammarsByScopeName[grammar.scopeName] = grammar
+    @trigger 'grammar-added', grammar
 
   removeGrammar: (grammar) ->
     _.remove(@grammars, grammar)

src/packages/status-bar/spec/status-bar-spec.coffee

@@ -183,7 +183,6 @@ describe "StatusBar", ->
     beforeEach ->
       atom.activatePackage('text.tmbundle', sync: true)
       atom.activatePackage('javascript.tmbundle', sync: true)
-      syntax.trigger 'grammars-loaded'
 
     it "displays the name of the current grammar", ->
       expect(statusBar.find('.grammar-name').text()).toBe 'JavaScript'