What is the equivalent of toJSON in testing-library/react?

Question

In @testing-library/react-native I have a method provided by render called toJSON which I use to compare the resulting output

    const { toJSON } = render(<HocText>simple string</HocText>);
    const { toJSON: expectedToJSON } = render(<Text>simple string</Text>);
    expect(toJSON()).toStrictEqual(expectedToJSON());

I am trying to find the equivalent of it in @testing-library/react.

I tried

    const { asFragment } = render(<HocMyComponent text="should be as is" />);
    const { asFragment: expectedAsFragment } = render(<span>should be as is</span>);
    expect(asFragment()).toStrictEqual(expectedAsFragment());

But the result was a failure because it is missing my data.

score 2 · Accepted Answer · answered Jan 05 '23 at 12:22

asFragment was the correct one.

It as actually a bug on the test. But it was a bit hard to see so I had to do a serialization first.

type MyComponentProps = { text: string }
function MyComponent({ text }: MyComponentProps) {
  return <span data-testid="my-element">{text}</span>
}
const MyComponentWithRef = forwardRef<HTMLSpanElement, MyComponentProps>(({ text }, ref) => <span data-testid="my-ref-element" ref={ref}>{text}</span>)

describe("hoc", () => {

  it("simple component should work as expected", async () => {
    render(<MyComponent text="bar" />);
    expect(screen.getByTestId("my-element")).toHaveTextContent("bar");
  })
  it("should work with simple component", () => {
    const serializer = new XMLSerializer();
    const HocMyComponent = withHoc<MyComponentProps, MyComponentProps, HTMLSpanElement>(MyComponent);

    const { asFragment } = render(<HocMyComponent text="should be as is" />);
    expect(screen.getByTestId("my-element")).toHaveTextContent("should be as is");
    const renderedValue = serializer.serializeToString(asFragment());
    const { asFragment: expectedAsFragment } = render(<span data-testid="my-element">should be as is</span>);
    expect(renderedValue).toStrictEqual(serializer.serializeToString(expectedAsFragment()));
  });

But once I figured out what was wrong in the test. The resulting test is

  it("should work with simple component", () => {
    const HocMyComponent = withHoc<MyComponentProps, MyComponentProps, HTMLSpanElement>(MyComponent);

    const { asFragment } = render(<HocMyComponent text="should be as is" />);
    expect(screen.getByTestId("my-element")).toHaveTextContent("should be as is");
    const { asFragment: expectedAsFragment } = render(<span data-testid="my-element">should be as is</span>);
    expect(asFragment()).toStrictEqual(expectedAsFragment());
  });

What is the equivalent of toJSON in testing-library/react?

1 Answers1