Designing is an important stage to have a plan of action, but really the meat of the developing process is in the implementation.

Implementing the general architecture design will require multiple smaller design decisions about how the code needs to be structured and developed. It doesn't matter how good the design is, the execution is critical and will validate or adjust the prepared plan.

A solid implementation, then, requires developers to be skeptical about their own coding abilities and code needs to be tested thoroughly before it can be considered "done." This is a normal operation, and when done constantly, it produces good cascading effects, not only improving the quality of the code and reducing the number of problems but also increasing the capacity of the team to foresee weak points and harden them to be sure that, once in operation, the software is reliable and works with as few problems as possible.

We will see how to approach testing, including the use of Test-Driven Design (TDD), a practice that puts testing at the center of the development process.

Sometimes some code aspects need to be shared multiple times to be reused. A powerful tool in the Python world is the easy creation and sharing of modules that can be implemented. We will see how to structure, create, and maintain standard Python modules, including uploading them into PyPI, the standard Python repository of third-party packages.

This section of the book includes the following chapters:

• Chapter 10, Testing and TDD, explaining different approaches to testing, the Test-Driven Design methodology, and tools to write tests easily
• Chapter 11, Package Management, describing how to structure code to be shared to use in different parts of the system or to share it with the broader community