An Empirical Study of Test Generalization in NUnit Framework

Owing to the significance of unit testing in software development life cycle, there are several existing approaches on automating the generation of conventional unit tests. However, these approaches often fail to generate a minimal set of test cases for ensuring a high code coverage and manually writing such test cases is a labor-intensive task. To address these preceding issues with conventional unit tests, parameterized unit tests (PUT) are introduced where programmers can describe the expected behavior or specifications using symbolic values. Pex, an automatic test generation tool, accepts these PUTs and generates a minimal set of conventional unit tests that ensure a high code coverage. This process of converting conventional unit tests into PUTs is referred as test generalization. In our empirical study, we used an open source C# project called NUnit to study the benefits of test generalization. In our study, we found that the test generalization has increased the block coverage by 9.68% (on average) and also detected 7 new defects.