React Unit Testing Example 7

LoadingIndicator.test.js

  describe('when isLoading is true', () => {
    describe('given 200ms have elapsed', () => {
      it('should render loading indicator', () => {
        jest.useFakeTimers();
        const wrapper = mount(
          <LoadingIndicator isLoading={true}>
            <div>ahoy!</div>
          </LoadingIndicator>
        );
        jest.runAllTimers();
        expect(wrapper.html()).toBe(<div>loading...</div>);
        wrapper.unmount();
      });
    });
  });