What is developer testing (test-driven development)?

TDD (Test-Driven Development) is a software development methodology based on short iterations:

1. Writing a test: First, an automated test is written to check the functionality that is yet to be implemented. The test should be "red," meaning it should fail.
2. Writing minimal code: The minimal necessary code is written to pass the written test. The code can be written inefficiently.
3. Refactoring: Once the test becomes "green" (passes), the written code is refactored to improve it, maintain readability and structure, while ensuring the test remains "green."

The cycle repeats for each new part of functionality.

Main advantages:

• Improving code quality and design.
• Reducing the number of defects.
• Creating living documentation in the form of tests.
• Increasing confidence in changes thanks to regression tests.

Disadvantages:

• Requires more time at the initial stage.
• Can be difficult to apply to certain types of tasks (e.g., UI).
• Discipline is needed to follow the methodology rules.