Donate Fork on GitHub Issues

//junit.jens-piegsa.com/

Migration from JUnit 4 to JUnit 5

Introduction

Do I have to migrate all tests?

  • like in the transition from version three to four JUnit 4 and JUnit 5 tests can co-exist, in general there is no need to migrate all tests immediately

JUnit 4 to 5 migration recipes

Replace @Test imports

Replace @Before with @BeforeEach

Replace @After with @AfterEach

Replace @BeforeClass with @BeforeAll

Replace @AfterClass with @AfterAll

Replace HierarchicalContextRunner with @Nested

  • instead of @RunWith(HierarchicalContextRunner.class) on the top-level class, annotate all @Nested classes

Use @DisplayName("...")

  • annotate top-level test classes, @Nested test classes and @Test methods via @DisplayName("...") to better describe tested behaviour (you may like to form sentences along the nesting)

Migrate @Test(expected = Throwable.class)

@Test
void simpleExceptionTesting() {
    assertThrows(IllegalArgumentException.class, () -> {
        throw new IllegalArgumentException("a message");
    });
}

or

@Test
void advancedExceptionTesting() {
    final Throwable exception = 
            assertThrows(IllegalArgumentException.class, () -> {
        throw new IllegalArgumentException("a message");
    });
    assertEquals("a message", exception.getMessage());
}
  • or in BDD style use catch-exception like this:
import static com.googlecode.catchexception.apis.BDDCatchException.thenThrown;
import static com.googlecode.catchexception.apis.BDDCatchException.when;

class MyTest {
    @Test
    void catchExceptionTesting() {
        // given
        // ...
        
        when(() -> {
            throw new IllegalArgumentException("a message");
        });
        
        thenThrown(IllegalArgumentException.class);
    }
}

which requires this dependency in your pom.xml:

<dependency>
    <groupId>eu.codearte.catch-exception</groupId>
    <artifactId>catch-exception</artifactId>
    <version>2.0.0-beta-1</version>
    <scope>test</scope>
</dependency>

Mockito migration recipes

Replace usage of MockitoJUnitRunner with @ExtendWith(MockitoExtension.class)

  • add this dependency to your pom.xml:
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-junit-jupiter</artifactId>
    <version>${mockito.version}</version>
    <scope>test</scope>
</dependency>

import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.junit.jupiter.MockitoExtension;

@ExtendWith(MockitoExtension.class)
class MyTest { ... }

Snippets

How to assert exception message

import static com.googlecode.catchexception.apis.BDDCatchException.caughtException;
import static com.googlecode.catchexception.apis.BDDCatchException.when;
import static org.assertj.core.api.BDDAssertions.then;

@DisplayName("UserBuilder")
class UserBuilderTest {
	
    @Test
    @DisplayName("should raise IllegalArgumentException on missing username.")
    void shouldRaiseExceptionOnMissingUsername() {

        // given
        final UserBuilder userBuilder = new UserBuilder();

        when(() -> userBuilder.build());

        then(caughtException())
                .isInstanceOf(IllegalArgumentException.class)
                .hasMessageContaining("username");
    }
}
  • required Maven dependencies in pom.xml:
<dependency>
    <groupId>org.assertj</groupId>
    <artifactId>assertj-core</artifactId>
    <version>3.9.1</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>eu.codearte.catch-exception</groupId>
    <artifactId>catch-exception</artifactId>
    <version>2.0.0-beta-1</version>
    <scope>test</scope>
</dependency>

Additional material

Contribute

Feel free to fork this project, send me pull requests, and issues through the project’s GitHub page.