Enzyme returns null for prop on shallow rendered react component

If you want to test props passed in like that use mount like so:

  it('allows us to set props', () => {
    const wrapper = mount(<Foo bar="baz" />);
    expect(wrapper.props().bar).to.equal("baz");
    wrapper.setProps({ bar: "foo" });
    expect(wrapper.props().bar).to.equal("foo");
  });