fix($mdInteraction): clean up events on $rootScope destroy

this prevents unit tests from leaking memory

Fixes: angular#11493

Author: codymikol

src/core/services/interaction/interaction.js

@@ -33,15 +33,20 @@ angular
  * </hljs>
  *
  */
-function MdInteractionService($timeout, $mdUtil) {
+function MdInteractionService($timeout, $mdUtil, $rootScope) {
   this.$timeout = $timeout;
   this.$mdUtil = $mdUtil;
+  this.$rootScope = $rootScope;
 
+  // IE browsers can also trigger pointer events, which also leads to an interaction.
+  this.pointerEvent = 'MSPointerEvent' in window ? 'MSPointerDown' : 'PointerEvent' in window ? 'pointerdown' : null;
   this.bodyElement = angular.element(document.body);
   this.isBuffering = false;
   this.bufferTimeout = null;
   this.lastInteractionType = null;
   this.lastInteractionTime = null;
+  this.inputHandler = this.onInputEvent.bind(this);
+  this.bufferedInputHandler = this.onBufferInputEvent.bind(this);
 
   // Type Mappings for the different events
   // There will be three three interaction types
@@ -65,24 +70,41 @@ function MdInteractionService($timeout, $mdUtil) {
   };
 
   this.initializeEvents();
+  this.$rootScope.$on('$destroy', this.deregister.bind(this));
 }
 
+/**
+ * Removes all event listeners created by $mdInteration on the
+ * body element.
+ */
+MdInteractionService.prototype.deregister = function() {
+
+    this.bodyElement.off('keydown mousedown', this.inputHandler);
+
+    if ('ontouchstart' in document.documentElement) {
+      this.bodyElement.off('touchstart', this.bufferedInputHandler);
+    }
+
+    if (this.pointerEvent) {
+      this.bodyElement.off(this.pointerEvent, this.inputHandler);
+    }
+
+};
+
 /**
  * Initializes the interaction service, by registering all interaction events to the
  * body element.
  */
 MdInteractionService.prototype.initializeEvents = function() {
-  // IE browsers can also trigger pointer events, which also leads to an interaction.
-  var pointerEvent = 'MSPointerEvent' in window ? 'MSPointerDown' : 'PointerEvent' in window ? 'pointerdown' : null;
 
-  this.bodyElement.on('keydown mousedown', this.onInputEvent.bind(this));
+  this.bodyElement.on('keydown mousedown', this.inputHandler);
 
   if ('ontouchstart' in document.documentElement) {
-    this.bodyElement.on('touchstart', this.onBufferInputEvent.bind(this));
+    this.bodyElement.on('touchstart', this.bufferedInputHandler);
   }
 
-  if (pointerEvent) {
-    this.bodyElement.on(pointerEvent, this.onInputEvent.bind(this));
+  if (this.pointerEvent) {
+    this.bodyElement.on(this.pointerEvent, this.inputHandler);
   }
 
 };