View#subscribe subscribes to an event emitter

spec/stdlib/space-pen-extensions-spec.coffee

@@ -1,20 +1,25 @@
 {View, $$} = require 'space-pen'
+EventEmitter = require 'event-emitter'
 
 describe "SpacePen extensions", ->
   class TestView extends View
     @content: -> @div()
 
-  [view, parent, observeHandler] = []
+  [view, parent] = []
 
   beforeEach ->
     view = new TestView
     parent = $$ -> @div()
     parent.append(view)
-    observeHandler = jasmine.createSpy("observeHandler")
-    view.observeConfig "foo.bar", observeHandler
-    expect(view.hasParent()).toBeTruthy()
 
   describe "View#observeConfig(keyPath, callback)", ->
+    observeHandler = null
+
+    beforeEach ->
+      observeHandler = jasmine.createSpy("observeHandler")
+      view.observeConfig "foo.bar", observeHandler
+      expect(view.hasParent()).toBeTruthy()
+
     it "observes the keyPath and destroys the subscription when unsubscribe is called", ->
       expect(observeHandler).toHaveBeenCalledWith(undefined)
       observeHandler.reset()
@@ -32,9 +37,21 @@ describe "SpacePen extensions", ->
 
       expect(observeHandler).not.toHaveBeenCalled()
 
-    it "unsubscribes when the view is removed from the DOM", ->
+    it "unsubscribes when the view is removed", ->
       observeHandler.reset()
       parent.remove()
       config.foo = { bar: "hello" }
       config.update()
       expect(observeHandler).not.toHaveBeenCalled()
+
+  describe "View#subscribe(eventEmitter, eventName, callback)", ->
+    [emitter, eventHandler] = []
+
+    beforeEach ->
+      eventHandler = jasmine.createSpy 'eventHandler'
+      emitter = $$ -> @div()
+      view.subscribe emitter, 'foo', eventHandler
+
+    it "subscribes to the given event emitter and unsubscribes when unsubscribe is called", ->
+      emitter.trigger "foo"
+      expect(eventHandler).toHaveBeenCalled()

src/stdlib/space-pen-extensions.coffee

@@ -6,9 +6,13 @@ originalRemove = View.prototype.remove
 
 _.extend View.prototype,
   observeConfig: (keyPath, callback) ->
-    @subscribe(config.observe(keyPath, callback))
+    @addSubscription(config.observe(keyPath, callback))
 
-  subscribe: (subscription) ->
+  subscribe: (eventEmitter, eventName, callback) ->
+    eventEmitter.on eventName, callback
+    @addSubscription(destroy: -> eventEmitter.off eventName, callback)
+
+  addSubscription: (subscription) ->
     @subscriptions ?= []
     @subscriptions.push(subscription)