Extracting methods

The call to ReactDOM.render is the same in both methods. Since it's the same in both methods, it makes sense to pull it out.

However, rather than pull it out as-is, we can create a new function that takes the Appointment component as its parameter. This way, we can clearly see how our test data objects are woven through the object under test. If we hid that within an extracted method, the test would be less clear.

Above the first test, write the following definition:

const render = component => ReactDOM.render(component, container);

Now, replace the call to ReactDOM.render in each test with this line:

render(<Appointment customer={customer} />);

Re-run your tests now—they should still be passing.