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Prefer toBeRequired over checking properties (jest-dom/prefer-required)

💼 This rule is enabled in the ✅ recommended config.

🔧 This rule is automatically fixable by the --fix CLI option.

Rule Details

This rule aims to prevent false positives and improve readability and should only be used with the @testing-library/jest-dom package. See below for examples of those potential issues and why this rule is recommended. The rule is autofixable and will replace any instances of .toHaveProperty() or .toHaveAttribute() with toBeRequired() or not.toBeRequired as appropriate.

False positives

Consider these 2 snippets:

const { getByRole } = render(<input type="checkbox" required />);
const element = getByRole("checkbox");
expect(element).toHaveProperty("required"); // passes

const { getByRole } = render(<input type="checkbox" />);
const element = getByRole("checkbox");
expect(element).toHaveProperty("required"); // also passes 😱

Readability

Consider the following snippets:

const { getByRole } = render(<input type="checkbox" />);
const element = getByRole("checkbox");

expect(element).toHaveAttribute("required", false); // fails
expect(element).toHaveAttribute("required", ""); // fails
expect(element).not.toHaveAttribute("required", ""); // passes

expect(element).not.toHaveAttribute("required", true); // passes.
expect(element).not.toHaveAttribute("required", false); // also passes.

As you can see, using toHaveAttribute in this case is confusing, unintuitive and can even lead to false positive tests.

Examples of incorrect code for this rule:

expect(element).toHaveProperty("required", true);
expect(element).toHaveAttribute("required", false);

expect(element).toHaveAttribute("required");
expect(element).not.toHaveProperty("required");

expect(element).not.toBeRequired();
expect(element).not.not.toBeRequired();

Examples of correct code for this rule:

expect(element).not.toBeRequired();

expect(element).toBeRequired();

expect(element).toHaveProperty("aria-label", "foo");

expect(element).toHaveAttribute("alt");

When Not To Use It

Don't use this rule if you:

  • don't use jest-dom
  • want to allow .toHaveProperty('required', true|false);

Further reading