Refactoring

To achieve full code coverage, both the tests and the source code have to be refactored and tested several times to ensure that a robust and clean code is written. Refactoring should be iterative until full coverage is achieved. The refactoring step should remove duplicates from code and attempt to fix any signs of code smell.

The essence of TDD is to write clean code and in turn solid applications, depending on the type of tests being written (unit, acceptance, or integration tests). Refactoring can be localized to just a method or it can affect multiple classes. When refactoring, for example, an interface or multiple methods in a class, it is recommended you make the changes gradually, taking it one test at a time until all the tests and their implementation code are refactored.