How do I test higher-order components in TypeScript?

How do I test higher-order components in TypeScript?

To test higher-order components (HOCs) in TypeScript, you can use libraries like Jest and React Testing Library. Start by rendering the HOC with a mock component.

Can you show me a code example?

Sure! Here's a simple example:

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

const withExampleHOC = (WrappedComponent) => {
  return (props) => <WrappedComponent {...props} />;
};

const MockComponent = () => <div>Hello World</div>;
const EnhancedComponent = withExampleHOC(MockComponent);

test('renders the wrapped component', () => {
  const { getByText } = render(<EnhancedComponent />);
  expect(getByText('Hello World')).toBeInTheDocument();
});

This tests that the HOC correctly renders the wrapped component.

What if my HOC has props?

If your HOC has props, you can pass them down in the test. For example:

const EnhancedComponent = withExampleHOC(MockComponent);

test('renders with props', () => {
  const { getByText } = render(<EnhancedComponent someProp="Test" />);
  expect(getByText('Hello World')).toBeInTheDocument();
});

Make sure to adjust your MockComponent to utilize the props as needed.

Are there any best practices for testing HOCs?

Yes! Some best practices include:

1. Isolate the HOC logic from the wrapped component.
2. Use mock components to simplify tests.
3. Test both the HOC behavior and the wrapped component's behavior.