fix(selection-list): options not marked as selected if value is assigned too early (angular#9090)

Fixes the selection list options not being marked as selected if the component's value is set before `ngAfterContentInit`.

Fixes angular#9085.

Author: crisbeto

src/lib/list/selection-list.spec.ts

@@ -679,6 +679,22 @@ describe('MatSelectionList with forms', () => {
       expect(listOptions.every(option => !option.selected))
         .toBe(true, 'Expected every list option to be unselected.');
     });
+
+    it('should mark options as selected when the value is set before they are initialized', () => {
+      fixture.destroy();
+      fixture = TestBed.createComponent(SelectionListWithFormControl);
+      selectionListDebug = fixture.debugElement.query(By.directive(MatSelectionList));
+      selectionList = selectionListDebug.componentInstance;
+
+      fixture.componentInstance.formControl.setValue(['opt2', 'opt3']);
+      fixture.detectChanges();
+
+      listOptions = fixture.debugElement.queryAll(By.directive(MatListOption))
+        .map(optionDebugEl => optionDebugEl.componentInstance);
+
+      expect(listOptions[1].selected).toBe(true, 'Expected second option to be selected.');
+      expect(listOptions[2].selected).toBe(true, 'Expected third option to be selected.');
+    });
   });
 });
 

src/lib/list/selection-list.ts

@@ -290,6 +290,9 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements Focu
   /** View to model callback that should be called whenever the selected options change. */
   private _onChange: (value: any) => void = (_: any) => {};
 
+  /** Used for storing the values that were assigned before the options were initialized. */
+  private _tempValues: string[]|null;
+
   /** View to model callback that should be called if the list or its options lost focus. */
   onTouched: () => void = () => {};
 
@@ -301,6 +304,11 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements Focu
 
   ngAfterContentInit(): void {
     this._keyManager = new FocusKeyManager<MatListOption>(this.options).withWrap();
+
+    if (this._tempValues) {
+      this._setOptionsFromValues(this._tempValues);
+      this._tempValues = null;
+    }
   }
 
   /** Focus the selection-list. */
@@ -368,6 +376,8 @@ export class MatSelectionList extends _MatSelectionListMixinBase implements Focu
   writeValue(values: string[]): void {
     if (this.options) {
       this._setOptionsFromValues(values || []);
+    } else {
+      this._tempValues = values;
     }
   }