With this chapter, we have entered part two of our book, which covers the development of enterprise-grade applications using Python. While part one of this book focused on how to build an enterprise-grade application with scalability and performance in mind, part two of this book focuses on the internal development aspects of the application, such as how we can make sure our application is secure, how well it is performing, and how to ship an application with the higher quality checks in place so as to minimize the occurrence of unexpected behaviors during the production phase.

In this chapter, we would like to bring your focus to a very important aspect of the enterprise application development or, for that sake, an important aspect for the development of any kind of application. This important aspect is the testability of the code.

Writing code that can be easily tested can prove to be really useful. This involves the ability to identify bugs early in the application development phase, providing software with high quality standards, allowing for more and more automated testing of the code, and hence resulting in an application development process that is mature enough to release a stable application for the enterprise use cases.

Over the course of this chapter, we will learn about the following:

• The need for elaborate testing of the application code
• Different types of testing during the development life cycle
• Building a code base that can be tested easily
• Utilizing frameworks for improving our testing process
• Utilizing Continuous Integration/Continuous Delivery (CI/CD) pipelines for automating application testing