Mockito 2022-01-25

Unit testing with Mockito
Portland Java User Group
January 25, 2022

#java
#mockito

Transcript

1. Unit testing with Mockito Sean Sullivan Portland Java User Group January 25, 2022
2. Unit Tests
3. • Mockito library • Upgrading to Mockito 4 • Extending Mockito • Anti-patterns
4. Mockito is a framework for creating Mock objects
5. a Mock object mimics the behavior of a real object
6. Gilt.com checkout system
7. We wrote unit tests to verify: • happy path • edge case scenarios • error handling logic
8. • inventory reservation • payment system • shipping cost calculator • shipping restrictions • purchase limit service • tax calculator • discount calculator Gilt.com Checkout was dependent upon:
9. The test suite for Gilt.com Checkout used Mockito
10. We setup mock objects for: • Payment authorization • Inventory reservation • Discount redemption • Tax calculation • Shipping calculation
11. Maven pom.xml <dependency> <groupId>org.mockito</groupId> <artifactId>mockito-core</artifactId> <version>4.3.1</version> <scope>test</scope> </dependency>
12. import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import static org.mockito.Mockito.verify; import static org.mockito.ArgumentMatcher.any;
13. TaxEngine taxEngine = mock(TaxEngine.class); ShippingCostCalculator shippingCalc = mock(ShippingCostCalculator.class); when(taxEngine.calculate(any())).thenReturn(new Money(5, USD)); when(shippingCalc.calculate()).thenReturn(shippingInfo);
14. OrderManager unit test OrderManager manager = new OrderManager( taxEngine, shippingCalc); manager.sync(order); manager.submit(order); verify(taxEngine, once()).calculate(any()); assertTrue(order.isSubmitted());
15. Mockito.when
16. thenReturn
17. How do I mimic a failure?
18. use thenThrow
19. TaxEngine taxEngine = mock(TaxEngine.class); when(taxEngine.calculate(any(), any())) .thenThrow(new TaxViolationException());
20. Four major versions of Mockito • version 1.x • version 2.x • version 3.x • version 4.x
21. Upgrading to Mockito 4.x
26. async-http-client PR 1812
27. async-http-client PR 1812
28. async-http-client PR 1812
29. async-http-client PR 1812
30. async-http-client PR 1812
31. What if my company has 500 Git repos?
32. Automated refactoring tool
33. OpenRewrite https://moderne.io/
34. OpenRewrite
35. OpenRewrite
36. mockito.yml
37. Extending Mockito
38. Answer interface public interface Answer<T> { T answerInvocation(InvocationOnMock invocation); }
39. MockitoPlus library
40. MockitoPlus
41. MockitoPlus import static org.mockito.Mockito.mock; import static io.github.mockitoplus.MockitoPlus.when;
42. MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") .failAlternatingInvocations();
43. MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") . fi rstInvocationFails();
44. MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") .intermittentFailures() .randomDelay(Duration.of(500, MILLIS)); Intermittent failures with random delays
45. Mockito anti-patterns
46. // anti-pattern List<String> names = mock(List.class); // better List<String> names = new ArrayList<String>(); anti-pattern
47. // anti-pattern Optional<String> name = mock(Optional.class); // better Optional<String> name = Optional.of(“Obama”); anti-pattern
48. // anti-pattern CompletableFuture<String> f = mock(CompletableFuture.class); // better CompletableFuture<String> f = CompletableFuture.completedFuture(“bonjour”); anti-pattern
49. what about Scala?
51. “org.mockito” %% "mockito-scala" % “1.16.34” % Test build.sbt
52. import org.mockito.scalatest.MockitoSugar Scala trait
53. Questions?
54. The End @tinyrobots