The sections below should help given an overview of how to use CREDO, through worked examples.
The Using CREDO for System Testing of StGermain-based codes such as Underworld section explains how to use CREDO to run and set-up the basic system tests of a StGermain code that supercede the previous system testing scripts.
The Doing Model analysis with CREDO section shows examples of how to configure and run Underworld runs using CREDO, and analyse/post-process the results. This is for custom analysis, rather than for addition to the automated testing system.
The Scientific Benchmarking using CREDO section shows the more complex use-case of the code, where scientific benchmarks are set up: generally requiring both analysis-style set-up of models to run, while also using the system testing features to allow automated regular running of this benchmark.
The Different ways to launch CREDO scripts section gives examples of how to run CREDO scripts in different ways, including via PBS.
CREDO is designed in such a manner that it should be possible to readily convert analysis scripts into repeatable system tests, and after reading examples of all the sections above you should have a handle on how to go about this.