Automatic generation of oracles for exceptional behaviors

Test suites should test exceptional behavior to detect faults in errorhandling code. However, manually-written test suites tend to neglect exceptional behavior. Automatically-generated test suites, on the other hand, lack test oracles that verify whether runtime exceptions are the expected behavior of the code under test. This paper proposes a technique that automatically creates test oracles for exceptional behaviors from Javadoc comments. The technique uses a combination of natural language processing and run-time instrumentation. Our implementation, Toradocu, can be combined with a test input generation tool. Our experimental evaluation shows that Toradocu improves the fault-finding effectiveness of EvoSuite and Randoop test suites by 8% and 16% respectively, and reduces EvoSuite's false positives by 33%.