JTestMigBench and JTestMigTax: A benchmark and taxonomy for unit test migration

Unit tests play a critical role in improving software quality. However, writing effective unit tests from scratch is difficult and tedious. One way to reduce this difficulty is to recommend existing tests of semantically similar functions. However, modifying the recommended tests manually might still be difficult and tedious. For example, developers have to understand various code elements in the recommended tests to accurately replace them with semantically similar code elements from the target application. One way to mitigate the issue is by developing a test migration or reuse technique that could automatically transform the code elements in the recommended tests and migrate them to the target application. However, to develop such a technique, we first need to identify what types of code transformations are required to successfully migrate the recommended tests. Therefore, in this paper, we first recruit two external participants to create JTestMigBench, a benchmark of 510 manually migrated JUnit tests for 186 methods from five popular libraries. We then analyze the code changes in the migrated tests to create JTestMigTax, a taxonomy of test code transformation patterns. Our contributions provide the necessary foundations to develop automated unit test migration or reuse techniques.