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>
);
};
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
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
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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