refactor(connected-overlay-directive): avoid issues with property initialization

src/lib/core/overlay/overlay-directives.spec.ts

@@ -1,7 +1,7 @@
-import {ComponentFixture, TestBed} from '@angular/core/testing';
+import {ComponentFixture, TestBed, async} from '@angular/core/testing';
 import {Component, ViewChild} from '@angular/core';
 import {By} from '@angular/platform-browser';
-import {ConnectedOverlayDirective, OverlayModule} from './overlay-directives';
+import {ConnectedOverlayDirective, OverlayModule, OverlayOrigin} from './overlay-directives';
 import {OverlayContainer} from './overlay-container';
 import {ConnectedPositionStrategy} from './position/connected-position-strategy';
 import {ConnectedOverlayPositionChange} from './position/connected-position';
@@ -18,7 +18,7 @@ describe('Overlay directives', () => {
   beforeEach(() => {
     TestBed.configureTestingModule({
       imports: [OverlayModule],
-      declarations: [ConnectedOverlayDirectiveTest],
+      declarations: [ConnectedOverlayDirectiveTest, ConnectedOverlayPropertyInitOrder],
       providers: [
         {provide: OverlayContainer, useFactory: () => {
           overlayContainerElement = document.createElement('div');
@@ -111,6 +111,21 @@ describe('Overlay directives', () => {
         'Expected overlay to have been detached.');
   });
 
+  it('should not depend on the order in which the `origin` and `open` are set', async(() => {
+    fixture.destroy();
+
+    const propOrderFixture = TestBed.createComponent(ConnectedOverlayPropertyInitOrder);
+    propOrderFixture.detectChanges();
+
+    const overlayDirective = propOrderFixture.componentInstance.connectedOverlayDirective;
+
+    expect(() => {
+      overlayDirective.open = true;
+      overlayDirective.origin = propOrderFixture.componentInstance.trigger;
+      propOrderFixture.detectChanges();
+    }).not.toThrow();
+  }));
+
   describe('inputs', () => {
 
     it('should set the width', () => {
@@ -310,3 +325,14 @@ class ConnectedOverlayDirectiveTest {
 
   @ViewChild(ConnectedOverlayDirective) connectedOverlayDirective: ConnectedOverlayDirective;
 }
+
+@Component({
+  template: `
+  <button cdk-overlay-origin #trigger="cdkOverlayOrigin">Toggle menu</button>
+  <ng-template cdk-connected-overlay>Menu content</ng-template>`,
+})
+class ConnectedOverlayPropertyInitOrder {
+  @ViewChild(ConnectedOverlayDirective) connectedOverlayDirective: ConnectedOverlayDirective;
+  @ViewChild('trigger') trigger: OverlayOrigin;
+}
+

src/lib/core/overlay/overlay-directives.ts

@@ -10,6 +10,8 @@ import {
     Output,
     ElementRef,
     Renderer2,
+    OnChanges,
+    SimpleChanges,
 } from '@angular/core';
 import {Overlay, OVERLAY_PROVIDERS} from './overlay';
 import {OverlayRef} from './overlay-ref';
@@ -63,10 +65,9 @@ export class OverlayOrigin {
   selector: '[cdk-connected-overlay], [connected-overlay], [cdkConnectedOverlay]',
   exportAs: 'cdkConnectedOverlay'
 })
-export class ConnectedOverlayDirective implements OnDestroy {
+export class ConnectedOverlayDirective implements OnDestroy, OnChanges {
   private _overlayRef: OverlayRef;
   private _templatePortal: TemplatePortal;
-  private _open = false;
   private _hasBackdrop = false;
   private _backdropSubscription: Subscription;
   private _positionSubscription: Subscription;
@@ -125,6 +126,9 @@ export class ConnectedOverlayDirective implements OnDestroy {
   /** Strategy to be used when handling scroll events while the overlay is open. */
   @Input() scrollStrategy: ScrollStrategy = new RepositionScrollStrategy(this._scrollDispatcher);
 
+  /** Whether the overlay is open. */
+  @Input() open: boolean = false;
+
   /** Whether or not the overlay should attach a backdrop. */
   @Input()
   get hasBackdrop() {
@@ -135,16 +139,6 @@ export class ConnectedOverlayDirective implements OnDestroy {
     this._hasBackdrop = coerceBooleanProperty(value);
   }
 
-  @Input()
-  get open() {
-    return this._open;
-  }
-
-  set open(value: boolean) {
-    value ? this._attachOverlay() : this._detachOverlay();
-    this._open = value;
-  }
-
   /** Event emitted when the backdrop is clicked. */
   @Output() backdropClick = new EventEmitter<void>();
 
@@ -183,6 +177,12 @@ export class ConnectedOverlayDirective implements OnDestroy {
     this._destroyOverlay();
   }
 
+  ngOnChanges(changes: SimpleChanges) {
+    if (changes['open']) {
+      this.open ? this._attachOverlay() : this._detachOverlay();
+    }
+  }
+
   /** Creates an overlay */
   private _createOverlay() {
     if (!this.positions || !this.positions.length) {