Explain the process for unit testing and integration testing an Akka Streams application. What challenges might arise during testing, and how can they be addressed?
Unit testing Akka Streams involves isolating individual components, such as sources, flows, and sinks. TestKit provides tools like TestSource.probe, TestSink.probe, and TestFlow.probe for creating test probes to control and observe stream elements. Challenges include asynchronous behavior and backpressure handling.
Integration testing requires connecting multiple components together, simulating real-world scenarios. Use TestKit’s TestSubscriber.Probe and TestPublisher.Probe for controlling input/output of the entire stream. Challenges involve ensuring proper materialization, error handling, and stream completion.
Address challenges by using TestKit’s expect* methods (e.g., expectNext, expectError) to assert expected outcomes, within timeouts. Utilize async/await patterns or ScalaTest’s AsyncWordSpec for managing asynchronous tests. For backpressure, use TestPublisher.Probe’s expectRequest method to verify demand signals.
