Jest Enzyme test a React component that returns null in render method

问题

I have a component that returns null in render under certain conditions:

render() {
  if (this.props.isHidden) {
      return null;
  }

  return <div>test</div>;
}

I want to check if the component is null when isHidden is true with jest and enzyme:

describe('myComp', () => {
    it('should not render if isHidden is true', () => {
        const comp = shallow(<myComp isHidden={true} />);
        expect(comp.children().length).toBe(0);
    });
});

This works but is there a more idiomatic way to write this test ? Testing for components that render as null is quite a common scenario.

回答1:

   expect(comp.type()).toEqual(null)

That's it!

or: expect(comp.get(0)).toBeFalsy()

回答2:

According to ShallowWrapper::html implementation it returns null if component instance type is null, as a result of render.

expect(comp.html()).toBeNull();

回答3:

ShallowWrapper has a isEmptyRender() function:

expect(comp.isEmptyRender()).toBe(true)

来源：https://stackoverflow.com/questions/47259061/jest-enzyme-test-a-react-component-that-returns-null-in-render-method