refactor(nav): create NavControllerBase and public abstract class

Use NavController as the public API, and NavControllerBase as the
internal API. Refactored all app/nav/tabs unit tests and created
centralized mocking functions.

src/components/nav/nav-push.ts

@@ -1,28 +1,35 @@
-import { Directive, Input, Optional } from '@angular/core';
+import { Directive, HostListener, Input, Optional } from '@angular/core';
 
 import { NavController } from './nav-controller';
+import { noop } from '../../util/util';
 
 /**
  * @name NavPush
  * @description
- * Directive for declaratively linking to a new page instead of using
- * {@link ../NavController/#push NavController.push}. Similar to ui-router's `ui-sref`.
+ * Directive to declaratively push a new page to the current nav
+ * stack.
  *
  * @usage
  * ```html
  * <button [navPush]="pushPage"></button>
  * ```
- * To specify parameters you can use array syntax or the `nav-params` property:
+ *
+ * To specify parameters you can use array syntax or the `navParams`
+ * property:
+ *
  * ```html
- * <button [navPush]="pushPage" [navParams]="params"></button>
+ * <button [navPush]="pushPage" [navParams]="params">Go</button>
  * ```
- * Where `pushPage` and `params` are specified in your component, and `pushPage`
- * contains a reference to a [@Page component](../../../config/Page/):
+ *
+ * Where `pushPage` and `params` are specified in your component,
+ * and `pushPage` contains a reference to a
+ * [@Page component](../../../config/Page/):
  *
  * ```ts
- * import {LoginPage} from 'login';
+ * import { LoginPage } from './login';
+ *
  * @Component({
- *   template: `<button [navPush]="pushPage" [navParams]="params"></button>`
+ *   template: `<button [navPush]="pushPage" [navParams]="params">Go</button>`
  * })
  * class MyPage {
  *   constructor(){
@@ -32,61 +39,42 @@ import { NavController } from './nav-controller';
  * }
  * ```
  *
- * ### Alternate syntax
- * You can also use syntax similar to Angular2's router, passing an array to
- * NavPush:
- * ```html
- * <button [navPush]="[pushPage, params]"></button>
- * ```
  * @demo /docs/v2/demos/navigation/
  * @see {@link /docs/v2/components#navigation Navigation Component Docs}
  * @see {@link ../NavPop NavPop API Docs}
+ *
  */
 @Directive({
-  selector: '[navPush]',
-  host: {
-    '(click)': 'onClick()',
-    'role': 'link'
-  }
+  selector: '[navPush]'
 })
 export class NavPush {
 
   /**
-  * @input {Page} the page you want to push
-  */
-  @Input() navPush: any;
-
-  /**
-  * @input {any} Any parameters you want to pass along
-  */
-  @Input() navParams: any;
-
-  constructor(
-    @Optional() private _nav: NavController
-   ) {
-    if (!_nav) {
-      console.error('nav-push must be within a NavController');
-    }
-  }
-
-  /**
-   * @private
+   * @input {Page} The Page to push onto the Nav.
    */
-  onClick() {
-    let destination: any, params: any;
+  @Input() navPush: any[]|string;
 
-    if (this.navPush instanceof Array) {
-      if (this.navPush.length > 2) {
-        throw 'Too many [navPush] arguments, expects [View, { params }]';
-      }
-      destination = this.navPush[0];
-      params = this.navPush[1] || this.navParams;
+  /**
+   * @input {any} Parameters to pass to the page.
+   */
+  @Input() navParams: {[k: string]: any};
 
-    } else {
-      destination = this.navPush;
-      params = this.navParams;
+
+  constructor(@Optional() private _nav: NavController) {
+    if (!_nav) {
+      console.error('navPush must be within a NavController');
+    }
+  }
+
+  @HostListener('click')
+  onClick(): boolean {
+    // If no target, or if target is _self, prevent default browser behavior
+    if (this._nav) {
+      this._nav.push(this.navPush, this.navParams, noop);
+      return false;
     }
 
-    this._nav && this._nav.push(destination, params);
+    return true;
   }
+
 }