Test if a component is rendered with the right props with react-testing-library

Question

I have some components that are rendering another component (FetchNextPageButton) that is already tested in isolation, like these ones:

const News = () => (
          


        

Answer 1

This is the approach that Kent C. Dodds (the creator of RTL) shared with me after discussing it with him:

import FetchNextPageButton from 'FetchNextPageButton'

jest.mock('FetchNextPageButton', () => {
  return jest.fn(() => null)
})

// ... in your test
expect(FetchNextPageButton).toHaveBeenCalledWith(props, context)

Answer 2

Don't believe it's possible. RTL looks like focusing on validating against DOM not React's components tree.

The only workaround I see is to mock FetchNextPageButton to make it rendering all props into attributes.

jest.mock("../../../FetchNextPageButton.js", () => 
  (props) => <div data-test-id="FetchNextPageButton" {...props} />);
....
const { getByTestId } = render(<YourComponent />);
expect(getByTestId("FetchNextPageButton")).toHaveAttribute("query", NEWS_QUERY);
expect(getByTestId("FetchNextPageButton")).toHaveAttribute("path", "viewer.news");

Sure, this is smoothly only for primitive values in props, but validating something like object or function would be harder.

Think, it's not RTL-way, but I agree it would be massive work to check that in scope of each container(and completely ignoring that would be rather a risk).

PS toHaveAttribute is from jest-dom