How to test for tabIndex in Chai/Enzyme

Question

We're using Chai, Mocha and Enzyme. How can I test tabIndex?

This test works for className:

it('Renders a div with the default className of btn', () => {
  let wrapper = shallow(
    <Button className='btn' />,
  );
  expect(wrapper.find({ 'data-test': 'button' })).to.have.className('btn');
});

But this doesn't work for tabIndex:

it.only('Renders with the appropriate tabIndex', () => {
  let wrapper = shallow(
    <Button tabIndex={0} />,
  );

  expect(wrapper.find({ 'data-test': 'button' })).to.have.tabIndex('0');
  // undefined is not a constructor
});

EDIT: does this do what I need?

expect(wrapper.find({ 'data-test': 'button' }).prop('tabIndex')).to.equal(0);

It works, I'm not not 100% sure what I'm testing...