feat(accordion): add output for isOpen state changes

demo/src/app/components/+accordion/demos/basic/basic.html

@@ -9,10 +9,10 @@
     </div>
     This is just some content to illustrate fancy headings.
   </accordion-group>
-  <accordion-group heading="Content 1">
-    <p>Content 1</p>
+  <accordion-group heading="Group with isOpenChange event listener" (isOpenChange)="log($event)">
+    <p>Some content</p>
   </accordion-group>
-  <accordion-group heading="Content 2">
-    <p>Content 2</p>
+  <accordion-group heading="Another group">
+    <p>Some content</p>
   </accordion-group>
 </accordion>

demo/src/app/components/+accordion/demos/basic/basic.ts

@@ -4,4 +4,8 @@ import { Component } from '@angular/core';
   selector: 'demo-accordion-basic',
   templateUrl: './basic.html'
 })
-export class DemoAccordionBasicComponent {}
+export class DemoAccordionBasicComponent {
+  log(event: boolean) {
+    console.log(`Accordion has been ${event ? 'opened' : 'closed'}`);
+  }
+}

demo/src/ng-api-doc.ts

@@ -19,15 +19,20 @@ export const ngdoc: any = {
       {
         "name": "isOpen",
         "type": "boolean",
-        "description": "<p>Is accordion group open or closed </p>\n"
+        "description": "<p>Is accordion group open or closed. This property supports two-way binding </p>\n"
       },
       {
         "name": "panelClass",
         "type": "string",
         "description": "<p>Provides an ability to use Bootstrap&#39;s contextual panel classes\n(<code>panel-primary</code>, <code>panel-success</code>, <code>panel-info</code>, etc...).\nList of all available classes [available here]\n(<a href=\"http://getbootstrap.com/components/#panels-alternatives\" target=\"_blank\" title=\"null\">http://getbootstrap.com/components/#panels-alternatives</a>)</p>\n"
       }
     ],
-    "outputs": [],
+    "outputs": [
+      {
+        "name": "isOpenChange",
+        "description": "<p>Emits when the opened state changes </p>\n"
+      }
+    ],
     "properties": [],
     "methods": []
   },

src/accordion/accordion-group.component.ts

@@ -1,5 +1,5 @@
 import {
-  Component, HostBinding, Inject, Input, OnDestroy, OnInit
+  Component, HostBinding, Inject, Input, OnDestroy, OnInit, Output, EventEmitter
 } from '@angular/core';
 import { isBs3 } from '../utils/theme-provider';
 import { AccordionComponent } from './accordion.component';
@@ -29,27 +29,34 @@ export class AccordionPanelComponent implements OnInit, OnDestroy {
   @Input() panelClass: string;
   /** if <code>true</code> — disables accordion group */
   @Input() isDisabled: boolean;
+  /** Emits when the opened state changes */
+  @Output() isOpenChange: EventEmitter<boolean> = new EventEmitter();
 
   // Questionable, maybe .panel-open should be on child div.panel element?
-  /** Is accordion group open or closed */
+  /** Is accordion group open or closed. This property supports two-way binding */
   @HostBinding('class.panel-open')
   @Input()
   get isOpen(): boolean {
     return this._isOpen;
   }
 
   set isOpen(value: boolean) {
-    this._isOpen = value;
-    if (value) {
-      this.accordion.closeOtherPanels(this);
+    if (value !== this.isOpen) {
+      if (value) {
+        this.accordion.closeOtherPanels(this);
+      }
+      this._isOpen = value;
+      Promise.resolve(null).then(() => {
+        this.isOpenChange.emit(value);
+      });
     }
   }
 
   get isBs3(): boolean {
     return isBs3();
   }
 
-  protected _isOpen: boolean;
+  protected _isOpen = false;
   protected accordion: AccordionComponent;
 
   constructor(@Inject(AccordionComponent) accordion: AccordionComponent) {

src/spec/accordion.component.spec.ts

@@ -1,5 +1,5 @@
 import { Component } from '@angular/core';
-import { ComponentFixture, TestBed } from '@angular/core/testing';
+import { ComponentFixture, fakeAsync, TestBed, tick } from '@angular/core/testing';
 import { AccordionConfig } from '../accordion/accordion.config';
 
 import { AccordionModule } from '../accordion/accordion.module';
@@ -25,19 +25,19 @@ const html = `
   <accordion [closeOthers]="oneAtATime">
 
     <accordion-group heading="Panel 1"
-                     [isOpen]="panels[0].isOpen"
+                     [(isOpen)]="panels[0].isOpen"
                      [isDisabled]="panels[0].isDisabled">
       Content of panel 1
     </accordion-group>
 
     <accordion-group heading="Panel 2"
-                     [isOpen]="panels[1].isOpen"
+                     [(isOpen)]="panels[1].isOpen"
                      [isDisabled]="panels[1].isDisabled">
       Content of panel 2
     </accordion-group>
 
     <accordion-group heading="Panel 3"
-                     [isOpen]="panels[2].isOpen"
+                     [(isOpen)]="panels[2].isOpen"
                      [isDisabled]="panels[2].isDisabled">
       Content of panel 3
     </accordion-group>
@@ -166,4 +166,32 @@ describe('Component: Accordion', () => {
     fixture.detectChanges();
     expectOpenPanels(element, [false, false, false]);
   });
+
+  it('should modify the parent isOpen state when changed internally (2 way binding)', fakeAsync(() => {
+    const headingLinks = element.querySelectorAll('.accordion-toggle');
+
+    // Clicking (internal state modified)
+    headingLinks[0].click();
+    tick();
+    fixture.detectChanges();
+    expect(context.panels[0].isOpen).toBe(true);
+    expect(context.panels[1].isOpen).toBe(false);
+    expect(context.panels[2].isOpen).toBe(false);
+
+    // State modified by parent component
+    headingLinks[2].click();
+    tick();
+    fixture.detectChanges();
+    expect(context.panels[0].isOpen).toBe(false);
+    expect(context.panels[1].isOpen).toBe(false);
+    expect(context.panels[2].isOpen).toBe(true);
+
+    // Modified by binding
+    context.panels[1].isOpen = true;
+    fixture.detectChanges();
+    tick();
+    expect(context.panels[0].isOpen).toBe(false);
+    expect(context.panels[1].isOpen).toBe(true);
+    expect(context.panels[2].isOpen).toBe(false);
+  }));
 });