Test Driven Development uses the “test first” approach in which test cases and the unit tests are written before code is written. The unit tests are written by the developers and once the unit tests pass the developers start developing the application and code the application. The software development becomes a series of very short iterations in which test cases drive the creation of software and ultimately the design of the program. The unit tests forms the pillar for the development of the application in a TDD Development Environment.
Here is the flow of the Test Driven Development application development.