Mastering React Test-Driven Development

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.

The parts of a test that you want to see are the parts that differ between tests. Usually, some data remains the same (container in this example) and some differs (customer in this example). Do your best to hide away whatever is the same and proudly display what differs.

Above the first test, write the following ...