JUnit 5 - The Next Generation
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Talk was given for the first time at JPrime 2017 conference in Sofia, Bulgaria JUnit is the standard way to test things in Java. In fact, it is the most commonly included external library for Java projects! Here is another fact - JUnit 4 release was 11 years ago and no feature releases were added in recent years. What you knew about JUnit in 2010 is still 100% relevant today. In 2017... So finally, time for upgrade! What took 11 years? What is new? What changed and what stayed the same? What about IDE and build tool support? When is the release date? What will testing on the JVM look like in the future? Check the presentation and you will find out. For more info about JPrime check out jprime.io
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JUnit 5 - The Next Generation
- 1. kgolev.com@kotseto JUnit 5 Kostadin Golev CTO @ Rewards Labs The Next Generation
- 3. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 7. kgolev.com@kotseto How bad? Let’s rename some private variables to find out!
- 9. kgolev.com@kotseto 4.12-beta-1: org.junit.ComparisonFailure: expected: null<null> but was: null<null> 4.11: org.junit.ComparisonFailure: expected:<[1]L> but was:<[2]L> assertEquals(1, 2)
- 10. kgolev.com@kotseto Extension mechanism Runner @RunWith(SpringJUnit4ClassRunner.class) Rule @Rule ExpectedException thrown = none()
- 14. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 16. kgolev.com@kotseto There is no single JUnit 5 (JAR)
- 17. kgolev.com@kotseto Not one big fat jar We have more then ten now, in three groups
- 18. kgolev.com@kotseto JUnit Platform + JUnit Jupiter + JUnit Vintage JUnit 5
- 21. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 27. kgolev.com@kotseto @Test void exception() { RuntimeException thrown = assertThrows(RuntimeException.class, () -> library.throwRuntimeException("message") ); assertEquals("message", thrown.getMessage()); }
- 29. kgolev.com@kotseto What about Runners and Rules?
- 30. kgolev.com@kotseto We wrote some tests! How do we run them?
- 31. kgolev.com@kotseto Use JUnit 4 @RunWith(JUnitPlatform.class) provides limited JUnit 5 functionality
- 32. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 33. kgolev.com@kotseto Some History Or how JUnit 5 team discovered they were building a platform
- 34. kgolev.com@kotseto It started as a big fat jar Then everything got split in small, focused modules
- 35. kgolev.com@kotseto Launcher <<interface>> Engine Engine Impl Jupiter API implements JUnit Platform JUnit Jupiter
- 37. kgolev.com@kotseto <<interface>> Engine Engine Implementation implements JUnit Platform JUnit Jupiter
- 39. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3&4 Important New Features IDE & Tool Support
- 40. kgolev.com@kotseto You can still run your JUnit 3&4 tests But it will not be JUnit 3&4 running them
- 41. kgolev.com@kotseto Launcher <<interface>> Engine Vintage Engine Impl JUnit 3&4 API implements JUnit Platform JUnit Vintage
- 42. kgolev.com@kotseto JUnit Platform JUnit Jupiter JUnit Vintage JUnit5 tests JUnit4 tests
- 43. kgolev.com@kotseto Platform for the JVM Developers already started implementing their own engines, reusing JUnit5 tool integration
- 44. kgolev.com@kotseto Not only for Java Test Engine implementations exist for Scala, Kotlin and Groovy
- 45. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 47. kgolev.com@kotseto assertEquals(1, 2); assertEquals("String", "Another String"); org.opentest4j.AssertionFailedError: Expected :1 Actual :2
- 48. kgolev.com@kotseto assertAll( () -> assertEquals(1, 2), () -> assertEquals("String", “Another String") ) org.opentest4j.MultipleFailuresError: Multiple Failures (2 failures) expected: <1> but was: <2> expected: <String> but was: <Another String>
- 49. kgolev.com@kotseto What about Runners and Rules (again)? JUnit5 Extension model
- 52. kgolev.com@kotseto Composable & Powerful Use as many as you want whenever you want them
- 53. kgolev.com@kotseto @ExtendWith(SpringExtension.class) @ExtendWith(MockitoExtension.class) public class SpringTest { @Autowired SampleData sampleData; @Mock Dependency mockedDepedency;
- 54. kgolev.com@kotseto public class MockitoExtension implements TestInstancePostProcessor { @Override public void postProcessTestInstance( Object testInstance, ExtensionContext context) { MockitoAnnotations.initMocks(testInstance); } }
- 55. kgolev.com@kotseto Not many extensions yet a few unofficial ones Spring and Mockito support in next releases
- 57. kgolev.com@kotseto public class Library { private Books books; public Library(Books books) { this.books = books; } public void addBook(Book book) { // do something with books } }
- 58. kgolev.com@kotseto @Test void whenBookExistsThenIncrementAmount() {} @Test void whenBookExistsThenCheckAmountMoreThenN() {} @Test void whenBookDoesNotExistThenCreateBook() {} @Test void whenBookDoesNotExistThenSendNewBookNotification() {}
- 62. kgolev.com@kotseto Tests are often a tree, not a list
- 64. kgolev.com@kotseto @DisplayName("Book is added to library") class BookAddedTest { @DisplayName("when book exists") @Nested class whenBookExists { @DisplayName("amount++") @Test void incrementAmount() {} @DisplayName("check amount > limit") @Test void checkAmountMoreThenLimit() {} } . . . }
- 67. kgolev.com@kotseto @Test void strIsLessThenTenChar() { int value = "str".length(); assertTrue(value < 10); } @Test void StringIsLessThenTenChar() { int value = "String".length(); assertTrue(value < 10); }
- 71. kgolev.com@kotseto @ValueSource(strings = {“str”, “String”}) @ValueSource(ints = {1, 3, 7, 9}) @EnumSource(SomeEnum.class) @CsvSource({"1, 1", "2, 4", "4, 16”}) @CsvFileSource(resources=“testData.csv”)
- 72. kgolev.com@kotseto @MethodSource(names=“stringAndIntProvider") static Stream<Arguments> stringAndIntProvider() { return Stream.of( ObjectArrayArguments.create("foo", 3), ObjectArrayArguments.create("foobar", 6) ); }
- 74. kgolev.com@kotseto Why JUnit 5? Where Is It? Writing Tests Platform For The JVM Running Along JUnit 3 & 4 Important New Features IDE & Tool Support
- 75. kgolev.com@kotseto Supports latest release candidate Support in Oxygen 4.7 BETA Official support target 4.7.1 ETA: September 2017
- 76. kgolev.com@kotseto Surefire provider Plugin No native support (yet)