Rule-based systems are tested by developing a set of inputs which will produce already known outputs. The problem with this form of testing is that the system code is not considered when generating test cases. This makes software testing completeness difficult to measure. This is important because all the computational models are constructed within the code. Therefore, to show the models of the system are tested, it must be shown that the code is tested. Chem uses the Loci rule-based application framework to build computational fluid dynamics models. These models are tested using the Quick Test suite. The data flow structure built by Loci, along with Quick Test, provided a case study for the research. The test suite was compared against three levels of coverage. The measures indicated that the lowest level of coverage was not achieved. This shows us that structural coverage measures can be utilized to measure rule-based system testing completeness.