testRepositioning_whenDatePickerGrows_withFlagEnabled() {
    // Given a PopupDatePicker showing with KeepAllWeeksInViewport = true.
    popupDatePicker.setKeepAllWeeksInViewport(true);
    popupDatePicker.createDom();
    popupDatePicker.render();
    const datePicker = popupDatePicker.getDatePicker();
    const date = new DateDate();

    datePicker.setDate(date);
    popupDatePicker.showPopup(document.body, undefined /* opt_keepDate */);

    mockControl.createMethodMock(popupDatePicker.popup_, 'reposition');

    // Expect the PopupDatePicker to reposition.
    popupDatePicker.popup_.reposition().$once();

    mockControl.$replayAll();

    // When the DatePicker reports a size increase.
    datePicker.dispatchEvent(DatePicker.Events.GRID_SIZE_INCREASE);
    mockControl.$verifyAll();
  }
Tests that repositioning based on DatePicker growth happens if the flag is
enabled.
@suppress {visibility} suppression added to enable type checking