Jasmine test for changedMetadata method.

cms/static/coffee/spec/views/module_edit_spec.coffee

@@ -72,3 +72,14 @@ describe "CMS.Views.ModuleEdit", ->
       it "loads the .xmodule-display inside the module editor", ->
         expect(XModule.loadModule).toHaveBeenCalled()
         expect(XModule.loadModule.mostRecentCall.args[0]).toBe($('.xmodule_display'))
+
+    describe "changedMetadata", ->
+      it "returns empty if no metadata loaded", ->
+        expect(@moduleEdit.changedMetadata()).toEqual({})
+
+      it "returns only changed values", ->
+        @moduleEdit.originalMetadata = {'foo', 'bar'}
+        spyOn(@moduleEdit, 'metadata').andReturn({'a': '', 'b': 'before', 'c': ''})
+        @moduleEdit.loadEdit()
+        @moduleEdit.metadata.andReturn({'a': '', 'b': 'after', 'd': 'only_after'})
+        expect(@moduleEdit.changedMetadata()).toEqual({'b' : 'after', 'd' : 'only_after'})