Parameterized unit tests

TLDR

Parameterized unit tests extend industry practice by defining tests with parameters, separating external behavior specification from test case generation. The authors use symbolic execution and constraint solving to automatically select a minimal set of inputs for a parameterized unit test, and they implemented a prototype tool that generates these test cases. Parameterized unit tests can serve as symbolic summaries, enabling symbolic execution to scale, and the prototype tool was successfully applied to parts of the .NET base class library.

Abstract

Parameterized unit tests extend the current industry practice of using closed unit tests defined as parameterless methods. Parameterized unit tests separate two concerns: 1) They specify the external behavior of the involved methods for all test arguments. 2) Test cases can be re-obtained as traditional closed unit tests by instantiating the parameterized unit tests. Symbolic execution and constraint solving can be used to automatically choose a minimal set of inputs that exercise a parameterized unit test with respect to possible code paths of the implementation. In addition, parameterized unit tests can be used as symbolic summaries which allows symbolic execution to scale for arbitrary abstraction levels. We have developed a prototype tool which computes test cases from parameterized unit tests. We report on its first use testing parts of the .NET base class library.