A function which can be used in Angular component tests to trigger change detection for components using OnPush strategy.

on-push-change-detection.helper.ts

/**
 * Changes in components using OnPush strategy are only applied once when calling .detectChanges(),
 * This function solves this issue.
 */
export async function runOnPushChangeDetection(fixture: ComponentFixture<any>): Promise<void> {
  const changeDetectorRef = fixture.debugElement.injector.get<ChangeDetectorRef>(ChangeDetectorRef);
  changeDetectorRef.detectChanges();
  return fixture.whenStable();
}