¿should test contrary cases?

i am using tdd and i not sure if i should test contrary cases or only expected case.

test 1

test('should render loading placeholder if isloading = true', () => {
    const wrapper = shallow(
      <OrderDetails id="10" />
    );
    wrapper.setState({ isLoading: true });
    expect(wrapper.find(LoadingPlaceholder).length).toBe(1);
})

test 2

test('should not render loading placeholder if isloading = false', () => {
    const wrapper = shallow(
      <OrderDetails id="10" />
    );
    wrapper.setState({ isLoading: false});
    expect(wrapper.find(LoadingPlaceholder).length).toBe(0);
})

component

export default class OrderDetails extends PureComponent {
  state = {
    isLoading: true,
  }
  props: Props;
  render() {
    return (
      <div>
        {this.state.isLoading && (
           <LoadingPlaceholder />
        )}
      </div>
    )
  }
}

notes if only add the first test can pass the test with this for example unexpecected pass test

export default class OrderDetails extends PureComponent {
  state = {
    isLoading: true,
  }
  props: Props;
  render() {
    return (
      <div>
         <LoadingPlaceholder />
      </div>
    )
  }
}