be more willing to work with you on projects if you want to contribute to project that other programmers are working onyou'll be expected to show that your code passes existing tests and you'll usually be expected to write tests for new behavior you introduce to the project play around with tests to become familiar with the process of testing your code write tests for the most critical behaviors of your functions and classesbut don' aim for full coverage in early projects unless you have specific reason to do so testing your code