DatePickerElement

Full API (methods, signatures, descriptions): see api-reference.md. This note covers only behaviour that isn't obvious from the signatures.

String values use the localized format, LocalDate uses ISO

setValue(String) / assertValue(String) expect the localized display format dd/mm/yyyy (e.g. "15/05/2023"), whereas setValue(LocalDate) uses ISO-8601. Pick the overload that matches the format you're working with.

Asserting a cleared value

After clearing, assert emptiness with the LocalDate overload passing an explicit null cast to disambiguate:

date.clickClearButton();
date.assertValue((LocalDate) null);