I presented this talk to a Dev team at Alithya, Montreal, in September 2016.

1. JUnit5 –
The Next Generation of JUnit
Richard Langlois P. Eng.
Solutions Architect
10 août 2016

2.  Why JUnit5
 What is New
 Demo
 Migration Tips
10 août 2016
Agenda

3.  Junit 4 is an All-in-one library
 Difficult for IDEs to deal with the library.
10 août 2016
Why Junit 5

4.  Revamped codebase with a modular architecture.
 JUnit 5 = JUnit Platform + JUnit Jupiter + JUnit Vintage
 Junit Platform: Defines TestEngine API for developing a testing framework that
runs on the platform.
 Junit Jupiter: provides TestEngine for running Junit 5 based tests on the
platform.
 Junit Vintage: provides TestEngine for running Junit 3 and Junit 4 based tests on
the platform.
 Test code depends only on the JUnit 5 API.
 IDE support: As of August 2016, supported by IntelliJ IDEA 2016.2
 Milestone 2 released on July 23, 2016
 GA release (due late 2016).
 Code samples available on GitHub (https://github.com/junit-team/junit5-samples)
10 août 2016
What is Junit 5

5. MODIFIEZ LE STYLE DU TITRE
Architecture
• Test code depends only on the
JUnit 5 API.
• IDEs and build tools depend on
the Launcher and Engine APIs
and can execute tests
independent of the testing
framework in use.
10 août 2016

6.  JUnit 4
Import org.junit.Test
public class JUnit4Test {
@Test
public void aJunit4TestCase() {
assertTrue(“message”, 5 > 6);
}
}
 JUnit 5
Import org.junit.jupiter.api.Test
class JUnit5Test {
@Test
void aJunit5TestCase() {
assertTrue(5 > 6, “message”);
}
}
10 août 2016
JUnit 4 vs JUnit 5

7.  New set of annotations which resides in a different package
(org.junit.jupiter.api) than their JUnit 4 counterparts:
 @Test: the method is a test
 @TestFactory: the method is a test factory for dynamic tests
 @DisplayName: declares a custom display name (class or method)
 @BeforeEach: method executed before each test method
 @AfterEach: method executed after each test method
 @BeforeAll: method executed before all test methods
 @AfterAll: method executed after all test methods
 @Nested: denotes that the class is a nested, non-static test class
 @Tag: declare a tag for filtering tests (class or method)
 @Disabled: disable a test class or test method
 @ExtendWith: register custom extensions
10 août 2016
What is New

8.  New package org.junit.jupiter.api
 Tests do not need to be public
 Meta-Annotation: Allows to define our own composed
annotation
 Display Names with @DisplayName(“…”)
 Can contain spaces, special chars, and emoji 😱
 Assertions
 Optional message is now the last parameter
 Grouped assertions using assertAll()
 expectThrows: check that method throws an exception,
and returns the exception object to allow further testing.
10 août 2016
What is New (continued)

9.  Assumptions: Skip the test execution if the assumption
condition is not met.
 E.g. assumeTrue, assumingThat
 Disabling test with @Disabled
 Tagging: used to enable/disable tests with specific tags
in a build and execution
 Equivalent of the Categories in JUnit 4
 e.g. @Tag(“fast”).
 Nested Tests: Allow expressing relationship among
several group of tests.
10 août 2016
What is New (continued)

10.  Extension Model:
 New extension API that supersedes the
previous @RunWith and @Rule extension mechanism
 Test constructors and methods are now permitted to have
parameters enabling dependency injection.
 2 built-in resolvers:
 TestInfo: information about the current test (e.g. display name)
 TestReporter: to publish additional data about the current test
run
 Custom ParameterResolver: Specified with
@ExtendWith
10 août 2016
What is New (continued)

11.  Dynamic tests:
 A DynamicTest is a test case generated at runtime.
 Generated at runtime by a factory method (annotated with
@TestFactory).
 @TestFactory method returns a Stream, Collection,
Iterable or Iterator of DynamicTest instances.
10 août 2016
What is New (continued)

12. 1. AnnotationTestDemo.java
2. MetaAnnotationDemo.java
3. BeforeAfterDemo.java
4. DisplayNameDemo.java
5. AssertionsDemo.java
6. AssumptionsDemo.java
7. DisabledClassDemo.java
8. DisabledTestDemo.java
9. TaggingDemo.java
10. NestedTestDemo.java
11. ParameterTestInfoDemo.java
12. ParameterTestReporterDemo.java
13. DynamicTestDemo.java
10 août 2016
Demo

13.  Annotations reside in the org.junit.jupiter.api package.
 Assertions reside in org.junit.jupiter.api.Assertions.
 Assumptions reside in org.junit.jupiter.api.Assumptions.
 @Before and @After no longer exist; use @BeforeEach and
@AfterEach instead.
 @BeforeClass and @AfterClass no longer exist; use @BeforeAll and
@AfterAll instead.
 @Ignore no longer exists: use @Disabled instead.
 @Category no longer exists; use @Tag instead.
 @RunWith no longer exists; superseded by @ExtendWith.
 @Rule and @ClassRule no longer exist; superseded by @ExtendWith.
10 août 2016
JUnit 4 to JUnit 5 Migration Tips

14.  Project Homepage
 http://junit.org/junit5
 User Guide
 http://junit.org/junit5/docs/current/user-guide
 Javadoc
 https://junit.ci.cloudbees.com/job/JUnit5/javadoc
 GitHub
 https://github.com/junit-team/junit5
 Sample Projects
 https://github.com/junit-team/junit5-samples
 Twitter
 https://twitter.com/JUnitTeam
 Stack Overflow
 http://stackoverflow.com/tags/junit5
10 août 2016
References

15.  Questions?
 Next Lunch & Learn:
 Introduction to Docker, by John Okrasa
10 août 2016
Thank You !