@Test
public void testMakeOnCreationCallback() {

    final DatePickerDOMElement datePickerDomElement = mock(DatePickerDOMElement.class);
    final DatePicker datePickerWidget = mock(DatePicker.class);
    final String serverDate = "05-01-2018 06:00:00 +0300";
    final String dateConvertedFromServerTimezone = "05-01-2018 00:00:00 -0300";
    final Consumer<SingleValueDOMElement<Date, DatePicker>> callback = ConsumerFactory.makeOnCreationCallback(makeGridCell(asDate(serverDate)));
    when(datePickerDomElement.getWidget()).thenReturn(datePickerWidget);
    callback.accept(datePickerDomElement);
    verify(datePickerWidget).setValue(asDate(dateConvertedFromServerTimezone));
}