A short summary of the upcoming changes in JUnit 5.

1. Migrating to
JUnit 5 (alpha)

2. JUnit 4 JUnit 5
import org.junit.Test;
public class JUnit4Test {
@Test
public void aJunit4TestCase() {
// write test here
}
}
import org.junit.gen5.api.Test;
class JUnit5Test {
@Test
void aJunit5TestCase() {
// write test here
}
}

3. public @interface Test {
Class<? extends Throwable>
expected() default None.class;
long timeout() default 0L;
}
JUnit 4 JUnit 5
public @interface Test {
}
public @interface Before {}
public @interface After {}
public @interface BeforeEach {}
public @interface AfterEach {}
public @interface BeforeClass {}
public @interface AfterClass {}
public @interface BeforeAll {}
public @interface AfterAll {}
public @interface Ignore {
String value() default "";
}
public @interface Disabled {
String value() default "";
}

4. class FunctionalAssertionsWithHamcrest {
@Test
void testProcedural() {
File file = new File("/some/property.file");
assertTrue(file.exists());
}
@Test
void testFunctional() {
File file = new File("/some/property.file");
assertTrue(file::exists);
}
@Test
void testFunctionalGrouped() {
File file = new File("/some/property.file");
assertAll(() -> file.canWrite(), () -> file.canRead());
}
}

5. class AssumptionsAndExceptions {
@Test
void testFullyConditional() {
File file = new File("/some/property.file");
assumeTrue(file.exists());
runSomeRoutineDependingOn(file);
}
@Test
void testPartlyConditional() {
File file = new File("/some/property.file");
assumingThat(file.exists()), () -> {
runSomeRoutineDependingOn(file);
});
}
@Test
void testThrowsExcption() {
IOException exception = expectThrows(IOException.class, () -> {
new File("?").getCanonicalPath();
});
validate(exception);
}
}

6. JUnit 4 JUnit 5
public class ATest {
@Test
public void foo() {}
}
public class BTest {
@Test
public void bar() {}
}
@RunWith(Suite.class)
@Suite.SuiteClasses({
ATest.class,
BTest.class
})
public class MySuite {}
@Tag(SuiteA.class)
public class ATest {
@Test
public void foo() {}
}
@Tags(
@Tag(SuiteA.class),
@Tag(SuiteB.class)
)
public class BTest {
@Test
public void bar() {}
}

7. JUnit 4 JUnit 5
public class ATest {
@Test
public void foo() {}
}
public class BTest {
@Test
public void bar() {}
}
@RunWith(Suite.class)
@Suite.SuiteClasses({
ATest.class,
BTest.class
})
public class MySuite {}
@Tag(SuiteA.class)
public class ATest {
@Test
public void foo() {}
}
@Tag(SuiteA.class)
@Tag(SuiteB.class)
@Retention(RUNTIME)
public @interface Meta {}
@Meta
public class BTest {
@Test
public void bar() {}
}

8. @DisplayName("A stack")
class TestingAStack {
Stack<Object> stack = new Stack<Object>();
@Test @DisplayName("is empty") void isEmpty() {
Assertions.assertTrue(stack.isEmpty());
}
@Nested @DisplayName("after pushing an element")
class AfterPushing {
String anElement = "an element";
@BeforeEach void init() {
stack.push(anElement);
}
@Test @DisplayName("it is no longer empty") void isEmpty() {
Assertions.assertFalse(stack.isEmpty());
}
@Test @DisplayName("returns the element when popped")
void returnElementWhenPopped() {
Assertions.assertEquals(anElement, stack.pop());
}
}
}

9. class DependencyInjection {
@Test
void testSelfAware(TestInfo testInfo) {
String name = testInfo.getName();
assertTrue("selfAwareTest", name);
}
}
public interface TestInfo {
String getName();
String getDisplayName();
Set<String> getTags();
}

10. class DependencyInjection {
@Test
void testSelfReport(TestReporter testReporter) {
long start = System.nanoTime();
doHeavyLifting();
testReporter.publishEntry("time", System.nanoTime() - start);
}
}
public interface TestReporter {
void publishEntry(String key, String value);
void publishEntry(Map<String, String> values);
}

11. JUnit 4 JUnit 5
public @interface Rule {
String value() default "";
}
public @interface RunWith {
Class<? extends Runner> value();
}
public @interface ExtendWith {
Class<? extends Extension>[]
value();
}
interface ContainerExecutionCondition {...}
interface TestExecutionCondition { ... }
interface BeforeAllExtensionPoint { ... }
interface BeforeEachExtensionPoint { ... }
interface InstancePostProcessor { ... }
interface MethodParameterResolver { ... }
interface ExceptionHandlerExtensionPoint { ... }
interface AfterEachExtensionPoint { ... }
interface AfterAllExtensionPoint { ... }

12. @ExtendWith(FooExtension.class)
class FunctionalAssertionsWithHamcrest {
@Test
void testProcedural(@Foo File file) {
assertTrue(file.exists());
}
}
@Retention(RUNTIME)
@interface Foo {}
class FooExtension implements MethodParameterResolver {
@Override public boolean supports(Parameter parameter,
MethodInvocationContext methodInvocationContext,
ExtensionContext extensionContext) {
return parameter.isAnnotationPresent(Foo.class);
}
@Override public Object resolve(Parameter parameter,
MethodInvocationContext methodInvocationContext,
ExtensionContext extensionContext){
return new File("some/file");
}
}

13. Currently still unsupported:
1. Parameterized tests (no test-runner equivalent)
2. No test-timeout
3. No sorting of test methods
JInit 5 is work-in-progress and the development has slowed
down significantly. Tickets for M1 are up-for-grab on GitHub!

14. http://rafael.codes
@rafaelcodes
http://documents4j.com
https://github.com/documents4j/documents4j
http://bytebuddy.net
https://github.com/raphw/byte-buddy