OpenResty itself has been relying on automated testing to remain high quality over the years. As OpenResty core developers, we embrace the test driven development (TDD) process all the time. An excellent result of our TDD practices over the years is a huge set of test suites for all the OpenResty components. These test suites are so large as a whole, so it is impractical to run all the tests thoroughly on a single machine. A relatively large test cluster is often run on Amazon EC2 to run all these tests in all existing test modes. Lying at the heart of these test suites is usually the Test::Nginx test scaffold module developed by the OpenResty team.

The Test::Nginx scaffold provides a generic simple specification language for expressing and organizing test cases in an intuitive way. It also provides various powerful testing modes or "engines" to run the tests in various different ways in the hope of exposing bugs in different settings. It is also supported to extend the test specification language to add custom abstractions for advanced testing needs, usually found in application-level regression testing.