fix(material-experimental/mdc-list): ensure selection change event fires properly (#24174)

Leverages the new selection change event that we landed upstream
in MDC. The notify action adapter method was not suitable for the
event notification as it did not fire for e.g. CTRL + A selections
and was generally, semantically not guaranteed to fire on actual
interactive selections (like native controls emit the change event).

Author: devversion

src/material-experimental/mdc-list/selection-list.spec.ts

@@ -424,14 +424,7 @@ describe('MDC-based MatSelectionList without forms', () => {
       expect(listOptions.every(option => option.componentInstance.selected)).toBe(false);
     });
 
-    // This is temporarily disabled as the MDC list does not emit a proper event when
-    // items are interactively toggled with e.g. `CTRL + A`.
-    // TODO(devversion): look more into this. MDC does not expose an `onChange` adapter
-    // function. Authors are required to emit a change event on checkbox/radio change, but
-    // that is not an viable option for us since we also allow for programmatic selection updates.
-    // https://github.com/material-components/material-components-web/blob/a986df922b6b4c1ef5c59925107281d1d40287a8/packages/mdc-list/component.ts#L300-L308.
-    // tslint:disable-next-line:ban
-    xit('should dispatch the selectionChange event when selecting via ctrl + a', () => {
+    it('should dispatch the selectionChange event when selecting via ctrl + a', () => {
       const spy = spyOn(fixture.componentInstance, 'onSelectionChange');
       listOptions.forEach(option => (option.componentInstance.disabled = false));
       fixture.detectChanges();

src/material-experimental/mdc-list/selection-list.ts

@@ -398,8 +398,8 @@ function getSelectionListAdapter(list: MatSelectionList): MDCListAdapter {
 
       baseAdapter.setAttributeForElementIndex(index, attribute, value);
     },
-    notifyAction(index: number): void {
-      list._emitChangeEvent([list._itemsArr[index]]);
+    notifySelectionChange(changedIndices: number[]): void {
+      list._emitChangeEvent(changedIndices.map(index => list._itemsArr[index]));
     },
   };
 }