| Interface | Description | 
|---|---|
| TestExecutors.TestExecutorService | A union of the  ExecutorServiceandTestRuleinterfaces. | 
| Class | Description | 
|---|---|
| TestExecutors | A  TestRulethat validates that all submitted tasks finished and were completed. | 
| TestStreams | Utility methods which enable testing of  StreamObservers. | 
| TestStreams.Builder<T> | A builder for a test  CallStreamObserverthat performs various callbacks. |