| Tessy & IEC 61508 |
When considering programs written in C, we can treat a function in the sense of C as module according to IEC 61508. Hence, Tessy is a tool for module testing according to IEC 61508.
In table A.5 in the annexe of part 3 of IEC 61508, the technique/measure “Dynamic analysis and testing” is recommended at Safety Integrity Level (SIL) 1 and highly recommended at SIL 2 and higher. Because Tessy executes the test object during the tests, Tessy obviously performs dynamic testing. This technique/measure is further detailed in table B.2, where test case execution from boundary value analysis and from equivalence classes and input partition testing are mentioned. This is incorporated in Tessy by means of the Classification Tree Method respectively the Classification Tree Editor (CTE). Also in table B.2, structure-based testing is recommended at SIL 1 and 2 and highly recommended at SIL 3 and 4. Because Tessy can determine various coverage measures, Tessy can accomplish structure-based testing.
In table A.5, also “Functional and black-box testing” is highly recommended at all SILs. Because the specifications of the tests executed with Tessy base on the description of the expected behaviour of the test object (and not on the internals of the test object), the test performed by Tessy are functional and black-box.
If modifications of the software should take place, it shall be determined what software lifecycle phases have to be repeated (section 7.8.2.3). The scope of revalidation and testing has to be determined (section 7.8.2.6 b). It is likely, that module testing needs to be repeated. Also the documentation shall include the re-verification and revalidation of data and results (section 7.8.2.9). Because testing with Tessy is automated, it is easy to re-execute the tests and to create updated test documentation.
Tessy can be used at all SIL levels.