TextTest (as a standalone tool) consists of a core framework, which interprets a directory structure and the files in it a certain way, and the default configuration module , which is responsible for actually doing things (like running tests and evaluating the results). This default configuration comes with TextTest and is used unless you specify otherwise. But it is possible to override it with your own configuration and so tweak what it does. This allows you to take advantage of local circumstances: for example to plug in custom reporting tools for your application, or to take advantage of locally installed software. It also provides a way for you to add your own experimental features to TextTest without making it difficult to upgrade. Naturally, doing this involves writing code in Python.

In order to use a configuration other than the default one, specify the "config_module" entry in your config file. What this configuration will do is of course up to the person who wrote it, and hence in order to find this information out for a particular application, run "texttest -a <app> -help". This provides a means for configurations to explain how they differ from the default one.

If you write such a configuration module, the only requirement is that TextTest can import it, so it must be placed somewhere on PYTHONPATH. An additional trick is that you can place it in the root of your test suite in a directory called "texttest_config_modules", where it will also be picked up.

A configuration can both extend the range of command line options available, and the config file entries that will be interpreted and acted upon. Occasionally, they have defined new sorts of files that define test cases and test suites, besides the usual ones. It can then be useful to have the static GUI display them as such, so there is a config file entry “definition_file_stems” to allow this to be configured. They can be keyed with "regenerate" if they will also be produced by the program, like the default configuration's traffic and usecase files. Unix-style file expansions may be used to indicate a range of possible stems.

TextTest comes with 2 configurations to choose from - "default" which should work anywhere, and "queuesystem" for use on UNIX with the SGE or LSF grid engine installed.

There is a similar mechanism for the GUIs, whereby new configurations can extend the user interface to interface with some particular tool or environment. This is controlled by the config file entry “interactive_action_module”, which will default to the value of “config_module” with a "_gui" suffix added, if it is not explicitly defined. Your starting point for these modules is therefore the default_gui/__init__.py module.