What Is Test Driven Development and How Does It Improve Code Quality?

Test driven development is a software development practice where tests are written before the actual application code. In this approach, developers first create a test that defines the expected behavior of a feature. The code is then written specifically to pass that test, followed by refactoring to improve structure and maintainability. This cycle—often referred to as “red, green, refactor”—encourages disciplined development and ensures that functionality is continuously verified.

One of the main advantages of test driven development is that it promotes smaller, more focused code units that are easier to test and maintain. By validating functionality at the earliest stages of development, teams can detect defects quickly and reduce the cost of fixing issues later in the lifecycle. This approach also improves confidence when making changes, since existing tests act as a safety net.

In discussions around tdd vs bdd, test driven development is typically viewed as a developer-focused practice that strengthens code reliability through unit-level testing. While BDD emphasizes behavior and collaboration with business stakeholders, test driven development primarily focuses on improving code design and ensuring that each component functions correctly as the system evolves.