How Do You Test for the Non-existence of an Element Using Jest and React-testing-library?

How do you test for the non-existence of an element using jest and react-testing-library?

When writing tests for your React components using Jest and react-testing-library, it is important to ensure that your tests cover all possible scenarios, including the non-existence of certain elements. In this blog post, we will explore different approaches to test for the non-existence of an element using Jest and react-testing-library.

Approach 1: Using the queryByTestId method

The react-testing-library provides a variety of query methods to interact with elements in your component. One such method is queryByTestId, which returns the first element that matches the provided test ID or null if no element is found.

To test for the non-existence of an element, you can use queryByTestId and assert that the returned value is null.


import { render } from '@testing-library/react';

test('Element does not exist', () => {
const { queryByTestId } = render();
expect(queryByTestId('element-id')).toBeNull();
});


Approach 2: Using the querySelector method

If you prefer using CSS selectors to target elements, you can utilize the querySelector method provided by the container object returned by the render function.

In this approach, you can use querySelector with the desired CSS selector and assert that the returned value is null.


import { render } from '@testing-library/react';

test('Element does not exist', () => {
const { container } = render();
expect(container.querySelector('.element-class')).toBeNull();
});


Approach 3: Using the getByTestId method with expect.assertions

Another way to test for the non-existence of an element is by using the getByTestId method and the expect.assertions function provided by Jest.

In this approach, you can wrap the getByTestId method in the expect.assertions function and assert that the code throws an error.


import { render } from '@testing-library/react';

test('Element does not exist', () => {
expect.assertions(1);
try {
render();
expect(getByTestId('element-id')).toThrow();
} catch (error) {
expect(error.message).toMatch('Unable to find an element with the test ID');
}
});


By utilizing these approaches, you can effectively test for the non-existence of an element in your React components using Jest and react-testing-library.

Remember, thorough testing is crucial for ensuring the reliability and functionality of your code. Happy testing!