Not able to test customValueSetListener of ComboBox using UI unit Test

[mukherjeesudebi]

There is no api to trigger the customValueSetListener when setAllowCustomValue is true.

Code to test

@Route("combobox")
public class ComboBoxView extends VerticalLayout {
	private List<String> items = new ArrayList<>(Arrays.asList("Chrome", "Edge", "Firefox", "Safari"));

	public ComboBoxView () {
		TextField textField = new TextField();
		ComboBox<String> comboBox = new ComboBox<>("Browser");
		comboBox.setAllowCustomValue(true);
		comboBox.addCustomValueSetListener(e -> {
			String customValue = e.getDetail();
			items.add(customValue);
			comboBox.setItems(items);
			comboBox.setValue(customValue);
			textField.setValue(comboBox.getValue());
		});
		add(textField, comboBox);
		comboBox.setItems(items);
		comboBox.setHelperText("Select or type a browser");
	}
}

Test code

@Test
public void allowCustomTest() {
	navigate(ComboBoxView .class);
	TextField textField = $(TextField.class).first();
	ComboBox<String> comboBox = $(ComboBox.class).first();
	comboBox.setValue("Other");
	assertEquals("Other", textField.getValue());
}

Error : The test case fails as the listenerer was not called and TextField value is empty
Expected Outcome: The customValueSetListener should be invoked.

[mukherjeesudebi]

Workaround: To test an event listener for the custom value set event, we need to fire that event on the component itself.

@Test
public void allowCustomTest() {
	navigate(ComboBoxView.class);
	TextField textField = $(TextField.class).first();
	ComboBox<String> comboBox = $(ComboBox.class).first();
	ComponentUtil.fireEvent(comboBox, new CustomValueSetEvent<>(comboBox, true, "Other"));
	assertEquals("Other", textField.getValue());
}

[mshabarov]

ComboBox fires the event when the custom value is entered by end-user (javadoc):

a listener for the event which is fired when user inputs a string value that does not match any existing items

so setting a value programmatically doesn't trigger the listener.

I'd expect that ComboBox fires the event if you simulate a user input in the ComboBoxTester with a custom value. If this is not possible with the existing method in tester class, e.g. with selectItem, this needs to be added.