Returns whether or not the current node has a className prop including the passed in class name.
className(String): A single class name.
Boolean: whether or not the current node has the class.
const wrapper = mount(<MyComponent />);
expect(wrapper.find('.my-button').hasClass('disabled')).to.equal(true);.hasClass()expects a class name, NOT a CSS selector..hasClass('.foo')should be.hasClass('foo')