How to mock an event target value in Jasmine?

@lucile 

To mock an event target value in Jasmine, you can use the createEvent function to create a mock event object and set the target property to the desired mock event target value.

Here's an example of how you can do this:

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const mockEvent = document.createEvent('HTMLEvents');
mockEvent.initEvent('change', false, true);

const mockEventTarget = { value: 'new value' };
mockEvent.target = mockEventTarget;

// Now you can use the mock event object in your test, for example:
someFunctionUnderTest(mockEvent);

You can also use the spyOn function to spy on the addEventListener function and create a mock event object with the desired target value when the event listener is called. Here's an example of how you can do this:

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const mockEventTarget = { value: 'new value' };

spyOn(document, 'addEventListener').and.callFake((eventType, callback) => {
  const mockEvent = { target: mockEventTarget };
  callback(mockEvent);
});

// Now when the event listener is called, it will be passed the mock event object with the mock event target value.

You can also use a library like sinon to create mock event objects and set the target property to the desired value.

I hope this helps! Let me know if you have any questions.

@lucile 

In addition to the approaches mentioned above, here is an example of how you can mock an event target value in Jasmine using the spyOn method and a mock event object:

1. Define the function that you want to test, which listens for a change event:

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function handleChange(event) {
  console.log(event.target.value);
}

1. Define the test case using Jasmine, where you mock the event object and set the target value:

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describe('handleChange', () => {
  it('should handle change event with mocked target value', () => {
    const mockEvent = {
      target: { value: 'mocked value' }
    };

    spyOn(console, 'log');
    handleChange(mockEvent);

    expect(console.log).toHaveBeenCalledWith('mocked value');
  });
});

In this example, we create a mock event object with a mock target value, spy on the console.log function to track the output, call the handleChange function with the mock event, and finally assert that the console.log was called with the expected target value.

This approach allows you to mock the event target value in Jasmine tests effectively. Feel free to adjust the implementation based on your specific requirements. Let me know if you need any further clarification or assistance.