如何在Espresso测试中调用自定义视图上的方法？

onView(withId(R.id.custom_view)).perform(new ViewAction() {
    @Override
    public Matcher<View> getConstraints() {
        return isAssignableFrom(CustomView.class);
    }

    @Override
    public String getDescription() {
        return "Call customMethod() on CustomView";
    }

    @Override
    public void perform(UiController uiController, View view) {
        ((CustomView) view).customMethod();
    }
});