Unit Testing / Understanding Rx Java

Talk on understanding RxJava interfaces given at the NY Android meetup on 11/10/2015

Transcript

1. Unit Testing Rx API’s (Understanding Rx API’s) Trevor John Draft trevorrjohn @trevorrjohn
2. What We Will Cover Learn how RxJava APIs work (should work) How to use what we learned to write simple tests
3. Quick Overview Rx programming definition: An API for asynchronous programming with observable streams (http: //reactivex.io/) While the API is simple it is very large Most common use case is fetching data
4. RxJava Usage Allows you to simply handle responses while ignoring threading It allows for easier error handling Minimizes race conditions
5. Understanding How Rx Works Observable
6. Understanding How Rx Works Observable
7. Understanding How Rx Works Observable
8. Understanding How Rx Works Subscription
9. Understanding How Rx Works With Rx if nobody is listening it won’t do anything! No subscription, no anything (There are exceptions)
10. Unit Test It Unit test → Mock it!
11. WHOA!? Crazy right?! Not flexible Not practical What can we do? What if we want to use map?
12. WHOA!? The test doesn’t even work… :(
13. Observable Creation OnSubscribe interface? Subscriber?
14. Subscriber! I know those methods! Observable#subscribe() How data is passed back How does this help us test?
15. So what now?
16. Fake OnSubscribe Captures the subscriber Creates interface for notifying the subscriber
17. How Do We Use It? That looks good! Not tied to the implementation!
18. What is Better? 5* statements Reusable Magic? 11 statements Ridged Very straightforward
19. Another Option? Subjects! - They are super powerful and could be a better/simpler solution for testing. Less configurable, but it works and no “fake” classes
20. Common Smells Name your tests! @Test public void methodName_context_assertion() Keep tests short! Limit assertions per test
21. Questions?