An introduction to Unit Testing with CodeIgniter 4.
If you are unfamiliar with unit testing, start with some of the resources listed above. Unit testing allows us to break our code down into testable chunks and try to come up with all the scenarios where it should succeed, fail, or otherwise perform a certain way. Testing helps make sure we find our bugs and issues before production users, and gives other developers a chance to see examples of our project in use.
CodeIgniter 4 comes with unit tests ready to be run using the popular unit testing tool, PHPUnit. But since these tests are designed to validate the framework, developers will want to replace them with their own suite of tests for each project. That's where AppStarter testing scaffold comes in (go read the docs): a directory pre-configured for running tests against a project built in CodeIgniter 4. Read the docs in the main repository.
Example tests come as part of the playground in the tests directory. To run these, make sure all the dependencies are installed then type from the root of the project type:
composer test