Enzyme instance() returns null

问题

I have the following test:

describe('Form', () => {
  let store;
  let wrapper;

  beforeEach(() => {
    store = mockStore(mockData);
    wrapper = mount(
      <Provider store={store}>
        <Form />
      </Provider>
    );
  });

  it('handleForm calls uses validate() for validation', () => {
    const instance = wrapper.instance();
    const submitFormButton = wrapper.find('.submitFormButton');
    submitFormButton.simulate('click');
    console.log(instance); // null
  });
});

Any idea of what I'm doing wrong exactly?

I know that Enzyme has this thing:

NOTE: With React 16 and above, instance() returns null for stateless functional components.

but my functional component does have a state, I'm using hooks (if that changes anything) and there should be some way to access instance.componentMethod() still, right?

回答1:

NOTE: With React 16 and above, instance() returns null for stateless functional components.

With stateless component they mean actually here functional components. The instance() method is reserved for the class based component.

So you can use it for this component:

class Welcome extends React.Component {
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}

But not for this one:

function Welcome(props) {
  return <h1>Hello, {props.name}</h1>;
}

来源：https://stackoverflow.com/questions/60561427/enzyme-instance-returns-null