Simulating user input for TDD JavaScript

Question

I'm finding it increasingly difficult to simulate actual user events using jQuery or native element trigger functions. For example, if you have a text input and you don't want the user to be able to add a character, you can call e.preventDefault() with the jQuery-normalised event object on the keydown event. However, there is no way to programatically verify this test scenario.

The following test passes even without the call to preventDefault because the jQuery keydown trigger isn't a "real" event.

input.val('test').trigger(jQuery.Event({
    which: 68
});
expect(input).toHaveValue('test');

Without the correct code, this test should fail because the input should have a value of 'testd' (68 is the character code for 'd').

Does anyone know any methods or libraries to simulate real browser UI events?

Answer 1

Simulate real event is quite complicated. You must first determine which type of event you need and create it with document.createEvent. Then call different init*Event to initialize the event object. Finally, use element.dispatchEvent to dispatch the event to the target object.