introduction to testing the tdd cycle there is cycle to development when working in tdd manner the shortest form of this cycle is the tdd mantrared green refactor which relates to the unit testing suite of tools where it is possible to write unit test within tools such as pycharmwhen you run pyunit or pytest test test view is shown with red indicating that test failed or green indicating that the test passed hence red/greenin other words write the test and let it failthen implement the code to ensure it passes the last part of this mantra is refactor which indicates once you have it working make the code cleanerbetterfitter by refactoring it refactoring is the process by which the behaviour of the system is not changed but the implementation is altered to improve it the full tdd cycle is shown by the following diagram which highlights the test first approach of tddthe tdd mantra can be seen in the tdd cycle that is shown above and described in more detail below write single test run the test and see it fail implement just enough code to get the test to pass run the test and see it pass refactor for clarity and deal with any issue of reuse etc repeat for next test