Java Testing

Guidelines for writing tests in Java projects using the Spock Framework and Groovy.

When to use this skill

Writing new tests
Reviewing test code
Setting up test infrastructure
Configuring Testcontainers
Mocking dependencies in Spring Boot tests
When asked to "improve test setup" or "run all tests and fix"

Skill Contents

Sections

When to use this skill (L24-L32)
Quick Start (L58-L78)
Key Patterns (L79-L88)
Mocking Patterns (L89-L124)
Persistence Testing (L125-L140)
References (L141-L148)
Related Rules (L149-L153)
Related Skills (L154-L159)

Available Resources

📚 references/ - Detailed documentation

Quick Start

1. Test Structure

def "should do Y when X"() {
    given:
        // create test data
    when:
        // execute process
    then:
        // assert output
    where: // use test table if suited
}

2. Test Naming

Test files: <ClassName>Spec.groovy
Test methods: "should [expected behavior] when [condition]"

Key Patterns

| Pattern | When to Use | |---------|-------------| | Spock Mock | Unit tests without Spring context | | @SpringBean | Spring integration tests with mocks | | @ServiceConnection | Testcontainers database connection | | InProcessServer | gRPC client/server testing | | Data Tables | Multiple test cases with same structure |

Mocking Patterns

Unit Tests (No Spring)

class SomeSpec extends Specification {
    SomeInterface someInterface = Mock()

    def "test method"() {
        given:
            def underTest = new ClassUnderTest(someInterface)
        when:
            // call method
        then:
            1 * someInterface.someMethod("value") >> responseClass
    }
}

Spring Integration Tests

@SpringBootTest
class SomeSpec extends Specification {
    @SpringBean
    SomeInterface someInterface = Mock()

    def "test method"() {
        when:
            // call method
        then:
            1 * someInterface.someMethod(_) >> { throw new RuntimeException() }
    }
}

Persistence Testing

Use Testcontainers with @ServiceConnection for database tests:

@Configuration
class IntegrationTestConfiguration {
    @Bean
    @ServiceConnection
    PostgreSQLContainer<?> postgreSQLContainer() {
        return new PostgreSQLContainer<>("postgres:14-alpine")
                .withDatabaseName("test_db")
    }
}

References

| Reference | Description | |-----------|-------------| | references/spock-patterns.md | Advanced Spock patterns | | references/testcontainers-setup.md | Testcontainers configuration | | references/grpc-testing.md | gRPC test patterns |

Related Rules

java-testing-guidelines - Full testing reference
java-flyway-migrations - Flyway for test schema

Related Skills

| Skill | Purpose | |-------|---------| | java-coverage | JaCoCo test coverage | | gradle-standards | Test dependency bundles |