What aspect of TDD is most emphasized?

The aspect of Test-Driven Development (TDD) that is most emphasized is the practice of writing tests prior to code development. This approach is foundational to TDD and ensures that tests are defined based on the requirements of the system before any actual code is written. By starting with tests, developers clarify the expected behavior of the code and create a safety net that guides the implementation. This leads to more reliable code, as developers write only enough code to pass the tests, thereby minimizing unnecessary features and complexities.

The TDD cycle involves repeating the process of writing a failing test, writing just enough code to pass that test, and then refactoring the code while ensuring all tests still pass. This iterative process helps in creating high-quality software that meets requirements effectively and efficiently. In this light, the emphasis on writing tests first is not just a methodological choice but a strategic approach to ensuring code quality and alignment with specified functionalities.