fix(upgrade): add testability hook to downgraded component

Add testability hook to downgraded component so that protractor can wait for asynchronous call to complete.
Add unregisterApplication() and unregisterAllApplications() to testability registry for cleaning up testability and unit test.

packages/core/src/testability/testability.ts

@@ -67,12 +67,18 @@ export class Testability implements PublicTestability {
     });
   }
 
+  /**
+   * Increases the number of pending request
+   */
   increasePendingRequestCount(): number {
     this._pendingCount += 1;
     this._didWork = true;
     return this._pendingCount;
   }
 
+  /**
+   * Decreases the number of pending request
+   */
   decreasePendingRequestCount(): number {
     this._pendingCount -= 1;
     if (this._pendingCount < 0) {
@@ -82,6 +88,9 @@ export class Testability implements PublicTestability {
     return this._pendingCount;
   }
 
+  /**
+   * Whether an associated application is stable
+   */
   isStable(): boolean {
     return this._isZoneStable && this._pendingCount == 0 && !this._ngZone.hasPendingMacrotasks;
   }
@@ -102,13 +111,26 @@ export class Testability implements PublicTestability {
     }
   }
 
+  /**
+   * Run callback when the application is stable
+   * @param callback function to be called after the application is stable
+   */
   whenStable(callback: Function): void {
     this._callbacks.push(callback);
     this._runCallbacksIfReady();
   }
 
+  /**
+   * Get the number of pending requests
+   */
   getPendingRequestCount(): number { return this._pendingCount; }
 
+  /**
+   * Find providers by name
+   * @param using The root element to search from
+   * @param provider The name of binding variable
+   * @param exactMatch Whether using exactMatch
+   */
   findProviders(using: any, provider: string, exactMatch: boolean): any[] {
     // TODO(juliemr): implement.
     return [];
@@ -126,16 +148,48 @@ export class TestabilityRegistry {
 
   constructor() { _testabilityGetter.addToWindow(this); }
 
+  /**
+   * Registers an application with a testability hook so that it can be tracked
+   * @param token token of application, root element
+   * @param testability Testability hook
+   */
   registerApplication(token: any, testability: Testability) {
     this._applications.set(token, testability);
   }
 
+  /**
+   * Unregisters an application.
+   * @param token token of application, root element
+   */
+  unregisterApplication(token: any) { this._applications.delete(token); }
+
+  /**
+   * Unregisters all applications
+   */
+  unregisterAllApplications() { this._applications.clear(); }
+
+  /**
+   * Get a testability hook associated with the application
+   * @param elem root element
+   */
   getTestability(elem: any): Testability|null { return this._applications.get(elem) || null; }
 
+  /**
+   * Get all registered testabilities
+   */
   getAllTestabilities(): Testability[] { return Array.from(this._applications.values()); }
 
+  /**
+   * Get all registered applications(root elements)
+   */
   getAllRootElements(): any[] { return Array.from(this._applications.keys()); }
 
+  /**
+   * Find testability of a node in the Tree
+   * @param elem node
+   * @param findInAncestors whether finding testability in ancestors if testability was not found in
+   * current node
+   */
   findTestabilityInTree(elem: Node, findInAncestors: boolean = true): Testability|null {
     return _testabilityGetter.findTestabilityInTree(this, elem, findInAncestors);
   }