Görge Albrecht State of the Union

Transcription

1 @g_o_rge JUnit - State of the Union Görge Albrecht 206 JUnit State of the Union

2 Görge Albrecht Software Developer since 989 Freelance Code Mentor "taking care of code" Need help writing simpler code? Contact mentor.com mentor.com

3 History of JUnit

4 The Beginnings SUnit written by Kent Beck around 992 due to the lack of automatic testing possibilities JUnit created by Kent Beck and Erich Gamma around 997 JUnit became de facto standard of testing Java code Never in the field of software development was so much owed by so many to so few lines of code. Martin Fowler

5 JUnit 4 steady progress up to JUnit 3.8.x David Saff joined Kent Beck big architectural change from framework style (subclassing) to DSL Style (annotations) JUnit 4.4 added dependency to Hamcrest JUnit 4.7 added Rules to setting the context of a test

6 JUnit ƛ 0 Years since release of Junit 4 Java 8 introduced Lambdas not supported nor utilized by JUnit JUnit has always been a pet project Crowdfunding Campaign on Indiegogo to fund next generation of JUnit

7 JUnit 5 development started in Autumn 205 alpha release M released on M2 released on JUnit 5.0 GA expected by end of 206

8 Vision Decouple test execution and reporting from test definition and provisioning Rethinking JUnit s extensibility story Making use of Java 8 features

9 Lessons learned from JUnit 4 "If you release it, you re going to maintain it." Parameterized Hamcrest

10 JUnit 5 Core Principles Prefer extension points over features an extension point should be good at one thing It should be hard to write tests that behave differently based on how they are run Tests should be easy to understand Minimize dependencies (especially third-party)

11 Components JUnit Platform foundation for launching test frameworks JUnit Jupiter new programming model and extension model JUnit Vintage TestEngine for running JUnit 3 and JUnit 4 based tests on the platform Open Test Alliance for the JVM: opentest4j

12 Syntactic sugar

13 no publicanymore package com.codementor.junit5; import org.junit.jupiter.api.test; class NoPublicTest void name() {

14 Display names can be set on class ") class and method level") void name() {

15 Contract Tests I class ContractTest implements EqualsTester<String> public String value() { return public String equalvalue() { return public String nonequalvalue() { return "two";

16 Contract Tests II interface EqualsTester<T> { T value(); T equalvalue(); T default void twovaluesmustbeequal() { assertequals(value(), default void nonequalvaluesmustnotmatch() { assertnotequals(value(), nonequalvalue());

17 Contract Tests default void valuemustnotbeequaltonull() { assertnotequals(value(), default void samevaluemustbeequal() { assertequals(value(), value());

18 Contract Tests IV

19 Dynamic Test Stream<DynamicTest> dynamictestcreation() { return IntStream.iterate(2, n -> n * 2).limit(4).mapToObj( n -> dynamictest("test " + n, () -> asserttrue(n % 2 == 0)) ); IntelliJ support not complete void convinceintellijthisisatest() {

20 Nested new int ") class NestedClassesTest { private int count = void setcounttozero() { count is almost nothing ") void countiszero() { but after a step down ") class CountGreaterZeroTest void increasecount() { count++;

21 Nested Test Output

22 Assertions

23 Message comes last, void messagecomeslast() { org.junit.assert.assertequals( "JUnit <=4 message comes first", "astring", "astring"); org.junit.jupiter.api.assertions.assertequals( "astring", "astring", "JUnit 5 message comes last");

24 Lambdas void assertwithbooleanclassic() { void assertwithbooleanlambda() { asserttrue(() -> void assertwithbooleanmethodreference() { asserttrue(true::booleanvalue);

25 void exception() { expectthrows(runtimeexception.class, this::illegal); private void illegal() { throw new IllegalArgumentException("illegal");

26 Exception Message void exceptionmessageasssertion() { final RuntimeException exception = expectthrows(runtimeexception.class, this::illegal); assertequals("illegal", exception.getmessage()); private void illegal() { throw new IllegalArgumentException("illegal");

27 Lazy message void assertwithlambdamessage() { asserttrue( true, () -> "JUnit 5" + " message are evaluated " + "lazily");

28 Assert all properties at void assertallproperties() { Address address = new Address("New City", "Some Street", "No"); assertall( () -> assertequals("new City", address.city), () -> assertequals("irgendeinestraße", address.street), () -> assertequals("nr", address.number) );

29 Assumptions

30 void volkswageningdoesnotworkwithassumeasthisisreportedasaborted() { assumetrue(notonteststation()); void assumingthatisthekeytovolkswagening() { assumingthat(notonteststation(), () -> asserttrue(abgaswerteuntervorgabe()));

31 Extensions & Dependency Injection

32 Extensions replaced by Extensions registered class, method or annotation multiple extensions per element possible registered extensions are inherited

33 class MyTest void void test2() {

34 Extension Types I Conditional Test Execution ContainerExecutionCondition TestExecutionCondition Test Instance Post-processing TestInstancePostProcessor(MockitoExtension, SpringExtension) Parameter Resolution ParameterResolver

35 Extension Types II Test Lifecycle Callbacks BeforeAllCallback BeforeEachCallback BeforeTestExecutionCallback AfterTestExecutionCallback AfterEachCallback AfterAllCallback Exception Handling TestExecutionExceptionHandler

36 Dependency Injection JUnit 4.x: DI via Runner setting method parameters only one Runner per test class possible JUnit 4.7: DI fields in test class multiple fields if test methods had different dependencies JUnit 5: ParameterResolverFTW multiple ParameterResolverper test method possible each ParameterResolvercan handle different parameter types

37 DI example class @Test void test(@mock MyService service, TestContext context) {

38 Built-in ParameterResolver TestInfoParameterResolver provides test with context (name, tags, etc.) via TestInfoparameter works also on lifecycle callbacks TestReporterParameterResolver injects TestReporterinto test test can provide runtime information via TestReporterto execution env

39 Migration from JUnit 4

40 Remarks JUnit 5 is a complete rewrite neither compile nor binary compatibility bridges provided down- and upwards for smooth migration no need to update all existings tests

41 Execution JUnit 4 based Runner JUnitPlatformto run JUnit 5 tests in a JUnit 4 env JUnit Platform engine junit-vintage-engineto run JUnit 3 and 4 tests in a JUnit 5 env

42 Packages JUnit < 4 junit JUnit 4.x org.junit JUnit 5 org.junit.jupiter.api

43 JUnit 5 JUnit 4.x Assertions & Assumptions JUnit 5 JUnit 4.x o.j.j.a.assertions o.j.assert o.j.j.a.assumptions o.j.assume

44 JUnit 5 JUnit 4.x Annotations JUnit 5 JUnit @Category

45 JUnit 5 JUnit 4.x Lifecycle Annotations JUnit 5 @ClassRule

46 Thanks for mentor.com Software Quality Days, Vienna Erste Schritte mit JUnit 5 Workshop with Peter CodeCop Kofler, Lesbare Tests mit AssertJ Talk,