Add property filters to TextEditor::getDecorations methods

This makes it much easier to write tests that inspect the state of
decorations.

spec/display-buffer-spec.coffee

@@ -1085,6 +1085,12 @@ describe "DisplayBuffer", ->
         expect(oldProperties).toEqual decorationProperties
         expect(newProperties).toEqual type: 'gutter', class: 'two', id: decoration.id
 
+    describe "::getDecorations(properties)", ->
+      it "returns decorations matching the given optional properties", ->
+        expect(displayBuffer.getDecorations()).toEqual [decoration]
+        expect(displayBuffer.getDecorations(class: 'two').length).toEqual 0
+        expect(displayBuffer.getDecorations(class: 'one').length).toEqual 1
+
   describe "::setScrollTop", ->
     beforeEach ->
       displayBuffer.manageScrollPosition = true

src/display-buffer.coffee

@@ -883,23 +883,28 @@ class DisplayBuffer extends Model
   decorationForId: (id) ->
     @decorationsById[id]
 
-  getDecorations: ->
+  getDecorations: (propertyFilter) ->
     allDecorations = []
     for markerId, decorations of @decorationsByMarkerId
       allDecorations = allDecorations.concat(decorations) if decorations?
+    if propertyFilter?
+      allDecorations = allDecorations.filter (decoration) ->
+        for key, value of propertyFilter
+          return false unless decoration.properties[key] is value
+        true
     allDecorations
 
-  getLineDecorations: ->
-    @getDecorations().filter (decoration) -> decoration.isType('line')
+  getLineDecorations: (propertyFilter) ->
+    @getDecorations(propertyFilter).filter (decoration) -> decoration.isType('line')
 
-  getGutterDecorations: ->
-    @getDecorations().filter (decoration) -> decoration.isType('gutter')
+  getGutterDecorations: (propertyFilter) ->
+    @getDecorations(propertyFilter).filter (decoration) -> decoration.isType('gutter')
 
-  getHighlightDecorations: ->
-    @getDecorations().filter (decoration) -> decoration.isType('highlight')
+  getHighlightDecorations: (propertyFilter) ->
+    @getDecorations(propertyFilter).filter (decoration) -> decoration.isType('highlight')
 
-  getOverlayDecorations: ->
-    @getDecorations().filter (decoration) -> decoration.isType('overlay')
+  getOverlayDecorations: (propertyFilter) ->
+    @getDecorations(propertyFilter).filter (decoration) -> decoration.isType('overlay')
 
   decorationsForScreenRowRange: (startScreenRow, endScreenRow) ->
     decorationsByMarkerId = {}

src/text-editor.coffee

@@ -1310,33 +1310,48 @@ class TextEditor extends Model
 
   # Extended: Get all decorations.
   #
+  # * `propertyFilter` (optional) An {Object} containing key value pairs that
+  #   the returned decorations' properties must match.
+  #
   # Returns an {Array} of {Decoration}s.
-  getDecorations: ->
-    @displayBuffer.getDecorations()
+  getDecorations: (propertyFilter) ->
+    @displayBuffer.getDecorations(propertyFilter)
 
   # Extended: Get all decorations of type 'line'.
   #
+  # * `propertyFilter` (optional) An {Object} containing key value pairs that
+  #   the returned decorations' properties must match.
+  #
   # Returns an {Array} of {Decoration}s.
-  getLineDecorations: ->
-    @displayBuffer.getLineDecorations()
+  getLineDecorations: (propertyFilter) ->
+    @displayBuffer.getLineDecorations(propertyFilter)
 
   # Extended: Get all decorations of type 'gutter'.
   #
+  # * `propertyFilter` (optional) An {Object} containing key value pairs that
+  #   the returned decorations' properties must match.
+  #
   # Returns an {Array} of {Decoration}s.
-  getGutterDecorations: ->
-    @displayBuffer.getGutterDecorations()
+  getGutterDecorations: (propertyFilter) ->
+    @displayBuffer.getGutterDecorations(propertyFilter)
 
   # Extended: Get all decorations of type 'highlight'.
   #
+  # * `propertyFilter` (optional) An {Object} containing key value pairs that
+  #   the returned decorations' properties must match.
+  #
   # Returns an {Array} of {Decoration}s.
-  getHighlightDecorations: ->
-    @displayBuffer.getHighlightDecorations()
+  getHighlightDecorations: (propertyFilter) ->
+    @displayBuffer.getHighlightDecorations(propertyFilter)
 
   # Extended: Get all decorations of type 'overlay'.
   #
+  # * `propertyFilter` (optional) An {Object} containing key value pairs that
+  #   the returned decorations' properties must match.
+  #
   # Returns an {Array} of {Decoration}s.
-  getOverlayDecorations: ->
-    @displayBuffer.getOverlayDecorations()
+  getOverlayDecorations: (propertyFilter) ->
+    @displayBuffer.getOverlayDecorations(propertyFilter)
 
   decorationForId: (id) ->
     @displayBuffer.decorationForId(id)