Testing POST /todos

In this section, you're going to learn how to set up the test suite for the Todo API, similar to what we did in the test section, and we'll be writing two test cases for /todos. We're going to verify that when we send the correct data as the body, we get a 200 back with the completed doc, including the ID; and, if we send bad data, we expect a 400 back with the error object.