In most of the treatments of unit, functional, and integration testing, it is often recommended that you write the tests before the corresponding code itself is written. While this is generally considered to be a good practice for a variety of reasons (primarily allowing you to ensure that the code being written solves the problem that has been defined), for the sake of simplicity, we have waited until now to touch on this subject.

First, let's create a new test_settings.py file that is sibling to our existing settings.py. This new file will contain the application configuration constants that we want to use while running our test suite. Most importantly, it will contain the URI to a database that is not our application database, as follows:

SQLALCHEMY_DATABASE_URI = 'sqlite:////tmp/test_app.db'
DEBUG = True
TESTING = True