This set of tutorials starts with helping explain why testing is a good idea in the first place, it then takes a look at the different types of tests that ship with Drupal core and the various frameworks that makes those tests possible. After that bit of groundwork orientation is done we'll learn how test files are organized in the Drupal codebase and how we can run existing tests using a few different methods. Once we know how to execute our test suite, we'll dig into implementation examples for functional and unit tests.
Primary Author, Paul Mitchum
Paul Mitchum (Mile23 on drupal.org) has done work on Drupal's continuous integration project, is an active core contributor, and is one of the maintainers of the Examples project among his other roles.