When we started our Chat application in Chapter 2, Test Doubles with a Chat Application, the whole code base was contained in a single Python module. This module mixed both the application itself, the test suite, and the fakes that we needed for the test suite.
While that process fits well for the experimentation and hacking phase, it's not convenient for the long term. As we already saw in Chapter 3, Test-Driven Development while Creating a TODO List, it's possible to split tests into multiple files and directories and keep them separated from our application code.
As our project grows, the first step is to split our test suite from our code base. We are going to use the src directory for the code base and the tests directory for the test suite. The src directory in this case will contain the chat package, which contains the modules for the client and server code:
.
├── src
│ ├── chat
│ │ ├...
