1 Unit Testing

Unit testing is the practice of testing individual units or components of code in isolation, using automated tools and frameworks. Unit testing is essential for both XP and TDD, as it enables developers to check the functionality, performance, and reliability of their code before integrating it with other parts of the system. Unit testing also helps developers refactor their code and improve its design, as well as detect and fix bugs early. Unit testing should be done frequently and consistently, following coding standards and conventions.

2 Test-Driven Development

Test-driven development is a specific approach to unit testing, where developers write the tests before the code. The idea is to define the expected behavior and outcome of the code, and then write the code that passes the tests. This way, developers can ensure that their code meets the requirements and specifications, and that they do not write unnecessary or redundant code. Test-driven development also encourages developers to think from the user's perspective, and to focus on the value and quality of the software. Test-driven development is a core practice of XP, and it can also be applied to other agile methodologies.

3 Acceptance Testing

Acceptance testing is the practice of testing the software from the user's point of view, using scenarios and criteria that reflect the user's needs and expectations. Acceptance testing is also known as functional testing, user testing, or end-to-end testing. Acceptance testing is important for both XP and TDD, as it validates that the software delivers the desired functionality and usability, and that it satisfies the customer's and stakeholder's requirements. Acceptance testing should be done in collaboration with the customer or representative, and using automated tools and frameworks whenever possible.

4 Continuous Integration

Continuous integration is the practice of merging and testing the code from different developers or teams frequently and automatically, using tools and servers that run the tests and report the results. Continuous integration is beneficial for both XP and TDD, as it ensures that the code is always in a working state, and that any conflicts or errors are detected and resolved quickly. Continuous integration also enables faster feedback and delivery, as well as better collaboration and communication among developers and teams. Continuous integration should be done at least daily, or even several times a day, depending on the project size and complexity.

5 Exploratory Testing

Exploratory testing is the practice of testing the software without a predefined plan or script, using creativity and intuition to discover and investigate different aspects and features of the software. Exploratory testing is complementary to both XP and TDD, as it allows developers to find and fix issues that may not be covered by the other types of testing, and to explore new ideas and possibilities for improving the software. Exploratory testing also enhances the developer's understanding and learning of the software, as well as their engagement and motivation. Exploratory testing should be done periodically and spontaneously, using various tools and techniques.