The warning "refs cannot be assigned to function components" is a common issue when using Jest with TypeScript functional components. This warning occurs when you try to assign a ref to a functional component, which is not allowed since functional components don't have instances that can be referenced.
To handle this warning, there are a few options:
Convert the functional component to a class component. This will allow you to use refs as usual.
Use the React.forwardRef
API to pass the ref to a child component that is a class component.
Use a mock ref object in your tests. This involves creating a mock ref object that you pass to the component being tested, rather than a real ref. This can be a good solution if you don't need to test the specific behavior of the ref.
Here's an example of using React.forwardRef
:
import React, { forwardRef } from 'react';
interface Props {
// Props definition
}
const MyFunctionalComponent = forwardRef((props: Props, ref) => {
// The component implementation
});
export default MyFunctionalComponent;
And here's an example of using a mock ref object:
import React from 'react';
interface Props {
// Props definition
}
const MyFunctionalComponent: React.FC<Props> = ({ children }) => {
const ref = React.useRef(null);
// Component implementation using the mock ref object
return <div ref={ref}>{children}</div>;
}
export default MyFunctionalComponent;
In your test:
import React from 'react';
import { render } from '@testing-library/react';
import MyFunctionalComponent from './MyFunctionalComponent';
test('renders the component', () => {
const { container } = render(<MyFunctionalComponent />);
// Test the behavior of the mock ref object, if necessary
});
Asked: 2022-04-03 11:00:00 +0000
Seen: 11 times
Last updated: Jan 08 '23