Function expectValueChangeEvent

packages/forms/test/reactive_integration_spec.ts:1155–1164

(
      event: ControlEvent<T> | undefined,
      value: T,
      sourceControl: AbstractControl,
    )

    type ControlEvents<T extends AbstractControl> = UnwrapObservable<T['events']>[];

    function expectValueChangeEvent<T>(
      event: ControlEvent<T> | undefined,
      value: T,
      sourceControl: AbstractControl,
    ) {
      const valueEvent = event as ValueChangeEvent<T>;
      expect(valueEvent).toBeInstanceOf(ValueChangeEvent);
      expect(valueEvent.source).toBe(sourceControl);
      expect(valueEvent.value).toEqual(value);
    }

    function expectPristineChangeEvent<T>(
      event: ControlEvent<T> | undefined,