JUnit 5 @ Solutions HH

Transcript

1. JUnit 5
   

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2. Christian Stein
   • Software developer @ MICROMATA Kassel/Bonn
   • JUnit 5 core team member since 2017
   • Github: https://github.com/sormuras
   • Twitter: @sormuras
   

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3. Marc Philipp
   • Staff Software Engineer @ in Karlsruhe
   • JUnit Maintainer since 2012
   • Twitter: @marcphilipp
   • Web: http://www.marcphilipp.de
   

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4. Programming Model
   

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5. DEMO
   https://github.com/marcphilipp/junit5-demo/tree/20170906-solutions.hamburg
   

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6. Meta Annotations
   Annotations can be combined to enable re-use:

   

   @Target(ElementType.METHOD)

   @Retention(RetentionPolicy.RUNTIME)

   @Tag("integration")

   @Test

   public @interface IntegrationTest {}
   Usage:

   

   @IntegrationTest

   void test() {}

   Equivalent:

   

   @Tag("integration")

   @Test

   void test() {}
   

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7. @ParameterizedTest Sources
   • @ValueSource(ints = { 1, 2, 3 })
   • @EnumSource(TimeUnit.class)
   • @MethodSource(names = "myProviderMethod")
   • @CsvSource({ "foo, 1", "bar, 2", "'baz, qux', 3" })
   • @CsvFileSource(resources = "/two-column.csv")
   • @ArgumentsSource(MyArgumentsProvider.class)
   • @YourCustomSource
   

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8. @Nested Tests
   @DisplayName("A stack")
   class TestingAStackDemo {
   @Test
   @DisplayName("is instantiated with new Stack()")
   void isInstantiatedWithNew() {/* ... */}
   @Nested
   @DisplayName("when new")
   class WhenNew {
   @BeforeEach
   void createNewStack() {/* ... */}
   @Test
   @DisplayName("is empty")
   void isEmpty() {/* ... */}
   // ...
   @Nested
   @DisplayName("after pushing an element")
   class AfterPushing {
   @BeforeEach
   void pushAnElement() {/* ... */}
   @Test
   @DisplayName("it is no longer empty")
   void isNotEmpty() {/* ... */}
   // ...
   }
   }
   }
   

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9. Dynamic Tests
   @TestFactory
   Stream dynamicTestsFromStream() {
   return IntStream.iterate(0, n -> n + 2).limit(100)
   .mapToObj(n -> dynamicTest("test" + n, () -> {
   assertTrue(n % 2 == 0);
   }));
   }
   

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10. @RepeatedTest
    @RepeatedTest(10)
    void repeatedTest() {
    // ...
    }
    

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11. Why do we need a new
    JUnit?
    

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12. Runner
    • Very powerful: Almost every aspect of test
    execution can be changed
    • But: You can only have one Runner per test class!
    • You can’t combine Runners, e.g.

    SpringJUnit4ClassRunner + Parameterized
    

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13. Rules
    • Extension mechanism introduced in JUnit 4.7
    • Wraps execution of a test (@Rule) or a test class
    (@ClassRule)
    • Designed to be combined — great for simple use cases
    • But: a single rule cannot be used for method-level and
    class-level callbacks, no support for instance-level callbacks
    

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14. http://blog.takipi.com/the-top-100-java-libraries-in-2016-after-analyzing-47251-dependencies/
    

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15. Existing Architecture
    Everyone uses the junit.jar.
    

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16. Renaming a private field should
    not break anything, right?
    4.11 4.12-beta-1
    

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17. –Johannes Link, https://jaxenter.com/crowdfunding-for-junit-lambda-is-
    underway-119546.html
    „The success of JUnit as a platform prevents the
    development of JUnit as a tool.“
    

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18. Design Goals for JUnit 5
    • Modern programming model for writing tests (Java 8!)
    • Powerful extension model with a focus on composability
    • API Segregation: Decouple test execution/reporting from test
    definition
    • Compatibility with older releases + migration path
    • Modularization + no external dependencies
    

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19. Modularization
    

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20. Separation of Concerns
    1. An API to write tests (Jupiter API)
    2. Extensible mechanisms to discover and execute
    tests (Test Engine SPI)
    3. An API for test execution by tools (Launcher API)
    

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21. P L AT F O R M
    J U P I T E R
    V I N TA G E
    P A R T Y
    T H I R D
    

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22. P L AT F O R M
    J U P I T E R
    V I N TA G E
    P A R T Y
    T H I R D
    

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23. JUnitPlatform Runner for a single class
    import org.junit.jupiter.api.Test;
    @RunWith(JUnitPlatform.class)
    public class JupiterTest {
    @Test
    void someTest() {
    // test something
    }
    }
    

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24. JUnitPlatform Runner in suite mode
    @RunWith(JUnitPlatform.class)
    @SelectPackages("com.acme")
    @IncludeEngines({"junit-jupiter", "junit-vintage"})
    public class JUnit4SuiteDemo {
    // this class can be run using JUnit 4
    }
    

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25. IDE Support
    • IntelliJ supports JUnit 5 ≥ M2 since 2016.2
    • Eclipse support is available on Eclipse Marketplace:

    https://marketplace.eclipse.org/content/junit-5-support-
    beta-oxygen

    Will be integrated without requiring any additional work
    in Oxygen.1a
    • Interim solution for other IDEs: JUnitPlatform Runner
    

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26. Build Tool Support
    • Gradle/Maven: Plugin/Provider available
    • see https://github.com/junit-team/junit5-
    samples
    • Manually: ConsoleLauncher
    

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27. Compatibility
    • Backward compatibility
    (junit-vintage-engine)
    enables gradual migration
    of tests to Jupiter API
    • Forward compatibility
    (JUnitPlatform Runner)
    allows test execution with
    “old” tools
    

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28. Extensions
    

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29. Extension Registration
    • Declarative: Annotate your test classes or methods with
    @ExtendWith to register extensions
    • Supports an arbitrary number of extensions at the
    same time
    • May be used as a meta-annotation
    • Global: Opt-in support for registration via ServiceLoader
    

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30. DEMO
    https://github.com/marcphilipp/junit5-demo/tree/20170906-solutions.hamburg
    

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31. Extension Points
    • Conditional Test Execution
    • ExecutionCondition
    • General Purpose
    • TestInstancePostProcessor
    • ParameterResolver
    • TestTemplateInvocationContext-
    Provider
    • Test Lifecycle Callbacks
    • BeforeAllCallback
    • BeforeEachCallback
    • BeforeTestExecutionCallback
    • TestExecutionExceptionHandler
    • AfterTestExecutionCallback
    • AfterEachCallback
    • AfterAllCallback
    

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32. Roadmap
    • 5.0 M4 (April 2017): parameterized and repeated tests ✔
    • 5.0 M5 (June 2017): dynamic containers, test instance lifecycle management, and
    minor API changes ✔
    • 5.0 M6 (July 2017): Java 9 compatibility, validation (e.g. tag syntax), and bug fixes ✔
    • 5.0 RC1, RC2, RC3 (July/August 2017): bug fixes and documentation improvements
    before GA. ✔
    • 5.0 GA (this week, really!): First general availability release
    • 5.1 (October?): additional features
    

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33. Summary
    

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34. What’s in it for me?
    • Modern programming model
    • Powerful extension points
    • Gentle migration path
    • Good tool support
    • Flexible platform/plugin architecture
    

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35. Getting Started
    User Guide:

    http://junit.org/junit5/docs/current/user-guide/
    Sample projects for Gradle and Maven:

    https://github.com/junit-team/junit5-samples
    Javadoc:

    http://junit.org/junit5/docs/current/api/
    

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36. Wanted: Feedback!
    Website:

    http://junit.org/junit5/
    Code & Issues:

    https://github.com/junit-team/junit5/
    Twitter:

    https://twitter.com/junitteam
    

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