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Mockito 2022-01-25
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sullis
January 25, 2022
Programming
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Mockito 2022-01-25
Unit testing with Mockito
Portland Java User Group
January 25, 2022
#java
#mockito
sullis
January 25, 2022
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Transcript
Unit testing with Mockito Sean Sullivan Portland Java User Group
January 25, 2022
Unit Tests
• Mockito library • Upgrading to Mockito 4 • Extending
Mockito • Anti-patterns
Mockito is a framework for creating Mock objects
a Mock object mimics the behavior of a real object
Gilt.com checkout system
We wrote unit tests to verify: • happy path •
edge case scenarios • error handling logic
• inventory reservation • payment system • shipping cost calculator
• shipping restrictions • purchase limit service • tax calculator • discount calculator Gilt.com Checkout was dependent upon:
The test suite for Gilt.com Checkout used Mockito
We setup mock objects for: • Payment authorization • Inventory
reservation • Discount redemption • Tax calculation • Shipping calculation
Maven pom.xml <dependency> <groupId>org.mockito</groupId> <artifactId>mockito-core</artifactId> <version>4.3.1</version> <scope>test</scope> </dependency>
import static org.mockito.Mockito.mock; import static org.mockito.Mockito.when; import static org.mockito.Mockito.verify; import
static org.mockito.ArgumentMatcher.any;
TaxEngine taxEngine = mock(TaxEngine.class); ShippingCostCalculator shippingCalc = mock(ShippingCostCalculator.class); when(taxEngine.calculate(any())).thenReturn(new Money(5,
USD)); when(shippingCalc.calculate()).thenReturn(shippingInfo);
OrderManager unit test OrderManager manager = new OrderManager( taxEngine, shippingCalc);
manager.sync(order); manager.submit(order); verify(taxEngine, once()).calculate(any()); assertTrue(order.isSubmitted());
Mockito.when
thenReturn
How do I mimic a failure?
use thenThrow
TaxEngine taxEngine = mock(TaxEngine.class); when(taxEngine.calculate(any(), any())) .thenThrow(new TaxViolationException());
Four major versions of Mockito • version 1.x • version
2.x • version 3.x • version 4.x
Upgrading to Mockito 4.x
None
None
None
None
async-http-client PR 1812
async-http-client PR 1812
async-http-client PR 1812
async-http-client PR 1812
async-http-client PR 1812
What if my company has 500 Git repos?
Automated refactoring tool
OpenRewrite https://moderne.io/
OpenRewrite
OpenRewrite
mockito.yml
Extending Mockito
Answer interface public interface Answer<T> { T answerInvocation(InvocationOnMock invocation); }
MockitoPlus library
MockitoPlus
MockitoPlus import static org.mockito.Mockito.mock; import static io.github.mockitoplus.MockitoPlus.when;
MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") .failAlternatingInvocations();
MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") . fi rstInvocationFails();
MockitoPlus HelloWorld hello = mock(HelloWorld.class); when(hello.sayHello(any())) .thenReturn("bonjour") .intermittentFailures() .randomDelay(Duration.of(500, MILLIS));
Intermittent failures with random delays
Mockito anti-patterns
// anti-pattern List<String> names = mock(List.class); // better List<String> names
= new ArrayList<String>(); anti-pattern
// anti-pattern Optional<String> name = mock(Optional.class); // better Optional<String> name
= Optional.of(“Obama”); anti-pattern
// anti-pattern CompletableFuture<String> f = mock(CompletableFuture.class); // better CompletableFuture<String> f
= CompletableFuture.completedFuture(“bonjour”); anti-pattern
what about Scala?
None
“org.mockito” %% "mockito-scala" % “1.16.34” % Test build.sbt
import org.mockito.scalatest.MockitoSugar Scala trait
Questions?
The End @tinyrobots