What is the essence of test-driven development (TDD)?

The essence of test-driven development (TDD) is fundamentally about writing tests before the actual coding takes place. This approach emphasizes the importance of defining the desired functionality through tests first, guiding developers to focus on requirements and expected behavior right from the start. By creating these tests beforehand, developers can clarify what the code needs to accomplish and ensure that each unit of code is developed with a clear purpose.

In TDD, the cycle typically follows a repetitive pattern of writing a test, running it to see it fail (since the code hasn't been implemented yet), writing the minimum amount of code necessary to pass the test, and then refactoring the code while keeping the tests green. This process not only supports better design and implementation but also fosters high test coverage and facilitates easier detection of bugs early in the development cycle.

This proactive approach inherently prioritizes quality and reliability through continuous feedback, directly aligning with the goals of quality assurance practices.