detect-changes.md

🏠   →   Documentation   →   Built-In Functionality   →   detectChanges

Other Predicates:   attributes ・ callLifeCycleHook ・call ・ clicked ・ debug ・ detectChanges ・ emit ・ provider ・ state ・ waitFakeAsync

---

This predicate runs change detection. It optionally takes a configuration parameter which allows to further tweak its behavior.

Signature

detectChanges(opts?: DetectChangesOptions);

Interface DetectChangesOptions

interface DetectChangesOptions {
  viaChangeDetectorRef?: boolean;
}

When setting viaChangeDetectorRef to true, this predicate will use the ChangeDetectorRef of the target(s) to enforce change detection. This is especially useful when the component-under-test uses ChangeDetectionStrategy.OnPush.

Examples

class the {
  static OnlineStatusIcon {
    return get(IconComponent);
  }
}

it('should show the online-state as icon', () => {
  When(host) // uses OnPush change-detection
    .has(state({ online: false }))
    .and(detectChanges({ viaChangeDetectorRef: true }))
    .expect(the.OnlineStatusIcon)
    .to(haveState({ icon: 'offline' }));
});