JUnit 5 - New Opportunities for Testing on the JVM

New Opportunities for Testing on the JVM

@sam_brannen

JUnit

@sam_brannen #JavaOne #JUnit5

Sam Brannen •  Spring and Java Consultant

•  Trainer, Coach, …

•  Hardcore developer at heart

•  Java Developer for about 20 years

•  Spring Framework Core Committer since 2007

•  JUnit 5 Core Committer since October 2015


Experts in Spring and Enterprise Java

Areas of expertise•  Spring *

•  JUnit 5

•  Java EE

•  Software Architecture

•  Code Reviews

Where you find us •  Zurich, Switzerland • @swiftmind

•  http://www.swiftmind.com


Agenda •  Impetus for Change

•  JUnit 5

•  Spring 5

•  Q & A


Show of hands …


Why a new version of JUnit?


Impetus for Change •  JUnit 4.0 was released a decade ago

•  a lot has changed since then…•  testing needs have matured

•  expectations have grown

•  Modularity à big ball of mud (i.e., only THE junit.jar)

•  Test discovery and execution à tightly coupled

•  Extensibility à lot of room for improvement

•  Let’s not forget Java 8 and Java 9


JUnit 4 Runner API •  Very powerful

•  In fact, it can do anything

•  But… you can’t combine Runners

•  Parameterized + SpringRunner à no way


JUnit 4… Rules… are meant to be broken •  JUnit 4.7: MethodRule à @Rule•  JUnit 4.9: TestRule à @Rule / @ClassRule

•  Great for simple use cases

•  Can even be combined

•  But… a single rule can’t be used for method-level and class-level callbacks

•  Plus… zero support for instance-level callbacks

•  Case in point: SpringClassRule / SpringMethodRule


JUnit Lambda – Crowdfunding Campaign •  Initiated by Johannes Link and Marc Philipp

•  Later joined by Matthias Merdes, Stefan Bechtold, & Sam Brannen

•  Ran from July to October 2015

•  Raised 53,937 Euros from 474 individuals and companies

•  4 companies donated 6 weeks of developer time


Thanks!


The Kick-off Team


JUnit 5


Roadmap •  Prototype à December 2nd, 2015

•  5.0.0-ALPHA à February 1st, 2016

•  6 Milestones à July 2016 – July 2017

•  2-3 Release Candidates à July 2017 – August 2017

•  5.0.0 GA à September 10th, 2017 ✅

•  5.0.1 à Today! (October 3rd, 2017) ✅


JUnit 5 – in a Nutshell •  Modular

•  Extensible

•  Modern

•  Forward and backward compatible

•  JUnit Platform supports JUnit 3.8, JUnit 4, and JUnit 5

•  New testing frameworks can be run with JUnit 4 infrastructureo  @RunWith(JUnitPlatform.class)


JUnit 5 – Java Versions •  Java 8

•  baseline

•  but can be used to test application code compiled against previous JDK versions

•  Java 9

•  #WorksFineOnJDK9

•  every artifact has a stable AUTOMATIC-MODULE-NAME•  module-path scanning support coming in 5.1


JUnit 5 = Platform + Jupiter + Vintage •  JUnit Platform 1.0.0

•  Foundation for launching testing frameworks on the JVM

•  Launcher and TestEngine APIs

•  ConsoleLauncher, Gradle plugin, Maven Surefire provider

•  JUnit Jupiter 5.0.0•  New programming model and extension model for JUnit 5

•  JUnit Vintage 4.12.0•  TestEngine for running JUnit 3 and JUnit 4 based tests

Revolutionary

Evolutionary

Necessary


Launcher API •  Used by IDEs and build tools to launch the framework

•  Central API for discovering and executing tests via one or more engines

•  LauncherDiscoveryRequest•  selectors and filters

•  Feedback provided via the TestExecutionListener API

•  ConsoleLauncher for command-line support


TestEngine API •  Test engine discovers and executes tests

•  for a particular programming model

•  Automatic registration via Java’s ServiceLoader mechanism

•  JupiterTestEngine

•  VintageTestEngine

•  Implement your own…


Third-party TestEngines •  Specsy

•  Spek

•  Cucumber

•  Drools Scenario

•  jqwik

source: https://github.com/junit-team/junit5/wiki/Third-party-Extensions

P L A T F O R M

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IDEs and Build Tools •  IntelliJ: ✅ IDEA 2016.2+

•  Eclipse: ✅ Eclipse Oxygen 4.7.1a (to be released next week)

•  NetBeans: 🙉🙈🙊

•  Gradle: interim solution from JUnit Team•  to be taken over by Gradle team (end of 2017)•  Android JUnit 5: third-party Android support

•  Maven: interim solution from JUnit Team•  being taken over by Maven Surefire team

See user guide andsample apps for examples


JUnit Jupiter – Extension Model •  Extension

•  marker interface

•  org.junit.jupiter.api.extension•  package containing all extension APIs •  implement as many as you like

•  @ExtendWith(...)•  used to register one or more extensions •  interface, class, or method level

o  or as a meta-annotation


Extension APIs •  BeforeAllCallback

•  BeforeEachCallback•  BeforeTestExecutionCallback•  AfterTestExecutionCallback

•  AfterEachCallback•  AfterAllCallback•  TestExecutionExceptionHandler •  ExecutionCondition•  TestInstancePostProcessor•  ParameterResolver•  TestTemplateInvocationContextProvider

Lifecycle Callbacks

Dependency Injection


JUnit Jupiter – Programming Model org.junit.jupiter.api (org.junit.jupiter.params)

•  Annotations and meta-annotations•  Assertions and Assumptions•  Custom display names•  Visibility•  Tagging•  Conditional test execution•  Dependency injection for constructors and methods•  Lambda expressions and method references•  Interface default methods•  Nested test classes•  Repeated tests, parameterized tests, dynamic tests


Annotations •  @Test / @TestFactory and @Testable for TestEngine implementors•  @RepeatedTest / @ParameterizedTest and @TestTemplate•  @Nested•  @TestInstance•  @BeforeAll / @AfterAll•  @BeforeEach / @AfterEach

•  @DisplayName•  @Tag•  @Disabled


JUnit 4 Rule Migration Support •  @EnableRuleMigrationSupport

o  located in experimental junit-jupiter-migrationsupport moduleo  registers 3 extensions for JUnit Jupiter

•  ExternalResourceSupporto  TemporaryFolder, etc.

•  VerifierSupporto  ErrorCollector, etc.

•  ExpectedExceptionSupporto  ExpectedExceptiono  minor bug in 5.0.0; fixed in 5.0.1


Assertions org.junit.jupiter.api.Assertions

•  Limited set of core assertions•  assertEquals(), assertNotNull(), etc.•  assertThrows() – λ•  assertTimeout() and assertTimeoutPreemptively() – λ•  assertAll() – λ

•  Supplier<String> à λ for lazy failure message evaluation•  message is now the last parameter

•  For more power, use AssertJ, Hamcrest, etc.


Assumptions org.junit.jupiter.api.Assumptions

•  Limited set of core assumptions

•  For aborting tests mid-flight

•  Otherwise, favor a custom ExecutionCondition for skipping

•  assumeTrue() / assumeFalse()•  BooleanSupplier, Supplier<String> – λ

•  assumingThat( ? , () -> {} ); – λ


LIVE CODING DEMO from JUnit 4 to JUnit Jupiter


Tagging

@Tag("fast")@Testvoid myFastTest() {}

•  Declare @Tag on a test interface, class, or method


Custom Tags

@Target(METHOD)@Retention(RUNTIME)@Tag("fast")public @interface Fast {}

•  Declare @Tag as a meta-annotation

@Fast@Testvoid myFastTest() {}


Composed Tags

@Target(METHOD)@Retention(RUNTIME)@Tag("fast")@Testpublic @interface FastTest {}

•  Declare @Tag as a meta-annotation with other annotations (JUnit, Spring, etc.)

@FastTestvoid myFastTest() {}


Test Names •  Names default to test class or test method names

•  characters limited based on Java syntax

•  Custom display names à @DisplayName•  Can contain spaces, special chars, and even emoji 😱


Dependency Injection •  Extension Model meets Programming Model

•  ParameterResolver extension API

•  resolves parameters for constructors or method

o  not just @Test and lifecycle methods

•  can register multiple simultaneously

•  only one wins

•  Use cases

•  server URL, DataSource, Spring ApplicationContext, etc.


TestInfo •  TestInfo: inject into constructor, @Test, @BeforeEach, etc.

•  access display name, tags, class, method

•  TestInfoParameterResolver•  eating our own dog food ;-)

•  See also:•  RepetitionInfo for @RepeatedTest•  TestReporter•  MockitoExtension•  SpringExtension


LIVE CODING DEMO tags, display names, and dependency injection


Conditional Test Execution •  Extension Model meets Programming Model

•  ExecutionCondition

•  @Disabled•  DisabledCondition

•  eating our own dog food ;-)

•  Deactivate via Launcher, system property, or junit-platform.properties file

•  junit.conditions.deactivate = org.junit.*

Game Changer


Interface Default Methods •  Introduces the concept of a test interface

•  Enables multiple inheritance in tests•  a.k.a., testing traits

•  @BeforeAll / @AfterAll•  if using @TestInstance(Lifecyle.PER_CLASS)

•  @BeforeEach / @AfterEach•  @Test / @RepeatedTest / @ParameterizedTest / @TestFactory•  @Tag•  @ExtendWith

•  See StringTests and TestInterfaceDemo examples in user guide


DEMO default methods


Nested Test Classes •  Enables logical, hierarchical grouping of test classes

•  with shared initialization and state from outer classes

•  Declare @Nested on non-static nested classes

•  i.e., inner classes

•  You can even combine nested classes and test interfaces

•  See TestingAStack example in user guide and Bowling Game Kata by Tim Riemer


DEMO nested test classes


Repeated Tests •  Annotate a method with @RepeatedTest instead of @Test

o  and specify the number of repetitions

•  Optionally have the RepetitionInfo injected as a method parameter

•  Optionally override the display name


@RepeatedTest in Action

@RepeatedTest(5)void repeatedTest(RepetitionInfo repetitionInfo) {

assertEquals(5, repetitionInfo.getTotalRepetitions());}

@RepeatedTest( value = 5, name = "Wiederholung {currentRepetition} von {totalRepetitions}”)void repeatedTestInGerman() {

// ...}


Parameterized Tests (junit-jupiter-params)

•  Annotate a method with @ParameterizedTest instead of @Testo  and specify the source of the arguments

o  optionally override the display name

•  Sources

o  @ValueSource: String, int, long, double

o  @EnumSourceo  @MethodSourceo  @CsvSource & @CsvFileSourceo  @ArgumentsSource & custom ArgumentsProvider


Argument Conversion •  Implicit conversion

o  Primitive types and their wrappers

o  Enums

o  java.time types (JSR-310)

•  Explicit conversion

o  @ConvertWith and custom ArgumentConvertero  @JavaTimeConversionPattern built-in support for JSR-310


@ParameterizedTest in Action

@ParameterizedTest@ValueSource(strings = { "mom", "dad", "radar", "racecar", "able was I ere I saw elba"})void palindromes(String candidate) {

assertTrue(isPalindrome(candidate));}


LIVE CODING DEMO repeated and parameterized tests


Dynamic Tests •  Conventional tests are static (i.e., known at compile time)

•  @Test

•  A DynamicTest is registered at runtime – λ•  as lambda expression in a stream, collection, etc.

•  by a method annotated with @TestFactory•  Can also register a DynamicContainer for dynamic nesting

•  Somewhat analogous to parameterized tests

•  just more… dynamic 🤓


Dynamic Tests in Action

@TestFactoryStream<DynamicTest> dynamicTestsFromIntStream() { // Generates tests for the first 10 even integers. return IntStream.iterate(0, n -> n + 2) .limit(10) .mapToObj(n -> dynamicTest("test" + n, () -> assertTrue(n % 2 == 0)));}


DEMO dynamic tests


What’s Missing? •  Scenario tests

•  Ordering

•  Parallel execution

•  Execution in user-defined thread

•  Declarative test suites for the JUnit Platform

•  Java 9 module-path scanning

•  …


Spring 5 + JUnit 5


Spring Support for JUnit Jupiter •  Fully integrated in Spring Framework 5.0!

•  released last week 😎

•  Supports all Core Spring TestContext Framework features

•  Constructor and method injection via @Autowired, @Qualifier, @Value•  Conditional test execution via SpEL expressions

•  ApplicationContext configuration annotations

•  Also works with Spring Framework 4.3

https://github.com/sbrannen/spring-test-junit5


Configuring JUnit Jupiter with Spring •  SpringExtension

•  @ExtendWith(SpringExtension.class)

•  @SpringJUnitConfig•  @ContextConfiguration + SpringExtension

•  @SpringJUnitWebConfig•  @SpringJUnitConfig + @WebAppConfiguration

•  @EnabledIf / @DisabledIf•  SpEL expression evaluation for conditional execution


DEMO Spring 5 and JUnit Jupiter

@EnabledOnMac / @DisabledOnMac


Spring Boot 1.4 + JUnit 5 – Custom Config

@Target(TYPE)@Retention(RUNTIME)

@ExtendWith(SpringExtension.class)@SpringBootTest(webEnvironment = MOCK)@AutoConfigureMockMvc@Transactionalpublic @interface SpringEventsWebTest {}

•  @SpringBootTest + @AutoConfigureMockMvc + @ExtendWith(SpringExtension.class)


Spring Boot 1.4 + JUnit 5 – MockMvc Test

@SpringEventsWebTestclass EventsControllerTests {

@Test @DisplayName("Home page should display more than 10 events") void listEvents(@Autowired MockMvc mockMvc) throws Exception { mockMvc.perform(get("/")) .andExpect(view().name("event/list")) .andExpect(model().attribute("events", hasSize(greaterThan(10)))); }}

•  @SpringEventsWebTest + method-level DI + MockMvc


In closing …


JUnit 5 Resources Project Homepage à http://junit.org/junit5

User Guide à http://junit.org/junit5/docs/current/user-guide

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

GitHub à https://github.com/junit-team

Gitter à https://gitter.im/junit-team/junit5

Stack Overflow à http://stackoverflow.com/tags/junit5


Spring Resources Spring Framework à http://projects.spring.io/spring-framework

Spring Guides à http://spring.io/guides

Spring JIRA à https://jira.spring.io

Spring on GitHub à https://github.com/spring-projects/spring-framework

Stack Overflow à spring, spring-test, spring-mvc, spring-boot, …


Additional JUnit 5 Talks @ JavaOne 2017 JUnit 5 BOF

Tuesday, Oct 03, 6:45 p.m. - 7:30 p.m. | Moscone West - Room 2016

JUnit5: Features, Architecture, and Extensibility

Wednesday, Oct 04, 2:45 p.m. - 3:30 p.m. | Moscone West - Room 2009


Demos Used in this Presentation https://github.com/sbrannen/junit5-demo


Q & A Sam Brannen

JUnit