enzyme containsMatchingElement with states

Iam having trouble figuring out why my test won't work. Lets say I have a component like this:

class MyComponent extends Component {
   constructor(props) {
      super(props);
      this.state = { flag: true };
   }
   render() {
      return (
         <div>
          {
            this.state.flag && (
               <div>Hello there!</div>
            )
          }
         </div>
      )
   }
}

Here is my test file:

it ('shows Hello There when the flag is set to true', () => {
  const component = shallow(<MyComponent />);
  component.setState({ flag: true });
  expect(
    component.containsMatchingElement(<div>Hello There</div>)
  ).toBe(true)
});

When I run this, it says that it is expecting true, but getting false. Am I doing something wrong?

Thanks!