[Performance] Update specs

Add tests to verify that directives stop polling after their
scope is destroyed (to prevent resource leaks); those changes
address resource leaks identified in the context of WTD-717.

platform/features/plot/test/MCTChartSpec.js

@@ -15,6 +15,7 @@ define(
                 mockElement,
                 mockCanvas,
                 mockGL,
+                mockCancelInterval,
                 mctChart;
 
             beforeEach(function () {
@@ -23,9 +24,10 @@ define(
                 mockLog =
                     jasmine.createSpyObj("$log", ["warn", "info", "debug"]);
                 mockScope =
-                    jasmine.createSpyObj("$scope", ["$watchCollection"]);
+                    jasmine.createSpyObj("$scope", ["$watchCollection", "$on"]);
                 mockElement =
                     jasmine.createSpyObj("element", ["find"]);
+                mockCancelInterval = jasmine.createSpy("cancelInterval");
 
 
                 // mct-chart uses GLChart, so it needs WebGL API
@@ -70,6 +72,7 @@ define(
 
                 mockElement.find.andReturn([mockCanvas]);
                 mockCanvas.getContext.andReturn(mockGL);
+                mockInterval.andReturn(mockCancelInterval);
 
                 mctChart = new MCTChart(mockInterval, mockLog);
             });
@@ -150,6 +153,26 @@ define(
                 expect(mockLog.warn).not.toHaveBeenCalled();
             });
 
+            // Avoid resource leaks
+            it("stops polling for size changes on destroy", function () {
+                mctChart.link(mockScope, mockElement);
+
+                // Should be listening for a destroy event
+                expect(mockScope.$on).toHaveBeenCalledWith(
+                    "$destroy",
+                    jasmine.any(Function)
+                );
+
+                // Precondition - interval still active
+                expect(mockCancelInterval).not.toHaveBeenCalled();
+
+                // Broadcast a $destroy
+                mockScope.$on.mostRecentCall.args[1]();
+
+                // Should have stopped the interval
+                expect(mockCancelInterval).toHaveBeenCalled();
+            });
+
         });
     }
 );