The function call syntax is, again, same as in C. Test bed variables and external variables declared in the code under test can be used as parameters and they can receive function return values. Also constant parameters can be used. The test beds can be run either interactively or through a test script. Scripts are text files containing the test calls expressed in the test bed command language. Because the test calls are expressed in terms of the module specification, they can be designed and stored in test scripts as early as at the module design phase, even if the implementation of the module is not yet available.
Script files can execute other script files.
There are various options for controlling the script execution. You can visit interactive mode in the middle of a script execution and define actions to be taken on syntax errors and assert failures. The test bed writes a trace listing file, which contains the commands executed during the test session and their output. The trace listing describes completely what was tested, when, how, and to which extent. Regression testing can be based on trace listings comparison.