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Lekshmi Chandra
Lekshmi Chandra

Posted on

Test for 'element exists?'- React testing library

Problem:

A react component is to being unit tested. The presence of an element after render is to be checked. In the following example, button with premium features is rendered conditionally.

Example:

const UserProfile: React.FC = user => {
  return (
    <div>
      <span>Hello {user.name}</span>
      {user.isPremiumUser && <button data-testid="premiumFeatures">Show premium features</button>}
    </div>
  );
};

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Test cases:

1. Check for presence

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

const { getByTestId } = render(
         <UserProfile user={{ name: 'Sheldon', isPremiumUser: false }} />
      );

expect(getByTestId('premiumFeatures')).toBeTruthy(); //passes

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2. Check for absence

When we use getByTestId to find an element and if it doesn't exist, getByTestId yells out an error which cannot be used to assert the absence.

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

const { getByTestId } = render(
         <UserProfile user={{ name: 'Sheldon', isPremiumUser:false }} />
      );

expect(getByTestId('premiumFeatures')).toBeFalsy(); //fails with unable find element with testid msg

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So, what can be used here is queryByTestId.

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

const { queryByTestId } = render(
         <UserProfile user={{ name: 'Sheldon', isPremiumUser: false }} />
      );

expect(queryByTestId('premiumFeatures')).toBeFalsy(); //passes

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