Writing tests for our application

Let's put our knowledge of unittest to work and write some tests for our application. To get started, we need to create a test module for our application. Make a directory called test inside the abq_data_entry package, and create the customary empty __init__.py file inside. We'll create all of our test modules inside this directory.

Testing our model

Our CSVModel code is fairly self-contained apart from its need to read and write files. Since file operations are one of the more common things that need to be mocked out in a test, the mock module provides mock_open, a Mock subclass ready-made to replace Python's open method. When called, a mock_open object returns a mock file handle object...