Test case generation with regular expressions and combinatorial techniques

A test case describes a specific execution scenario of the system under test (SUT). Its goal is to discover errors by means of its oracle, that emits a pass or fail verdict depending on the SUT behavior. The test case has a sequence of calls to SUT's operations with specific test data, which may come from the application of a combinatorial algorithm. This paper describes a method to describe generic test scenarios by means of regular expressions, whose symbols point to a SUT operation. The tester assigns values to each operation's parameter. A further step expands the regular expression and produces a set of operation sequences, which are then passed to a combinatorial algorithm to generate actual test cases. Regular expressions are annotated with a set of when clauses, that are processed by the combinatorial algorithm to include the oracle in the generated test cases.