Field-exhaustive testing

We present a testing approach for object oriented programs, which encompasses a testing criterion and an automated test generation technique. The criterion, that we call field-exhaustive testing, requires a user-provided limit n on the size of data domains, and is based on the idea of considering enough inputs so as to exhaustively cover the extension of class fields, within the limit n. Intuitively, the extension of a field f is the binary relation established between objects and their corresponding values for field f, in valid instances. Thus, a suite S is field-exhaustive if whenever a field f relates an object o with a value v (i.e., o.f = v) within a valid instance I of size bounded by n, then S contains at least one input I' covering such relationship, i.e., o must also be part of I', and o.f = v must hold in I'. Our test generation technique uses incremental SAT solving to produce small field-exhaustive suites: field-exhaustiveness can be achieved with a suite containing at most # F x n2 inputs, where # F is the number of fields in the class under test. We perform an experimental evaluation on two different testing domains drawn from the literature: implementations of data structures, and of a refactoring engine. The experiments show that field-exhaustive suites can be computed efficiently, and retain similar levels of code coverage and mutation killing as significantly larger bounded exhaustive and random suites, thus consuming a fraction of the cost of test execution compared to these automated testing approaches.