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
• Quick Start
• Key Patterns
• Mocking Patterns
• Persistence Testing
• References
• Related Rules
• Related Skills

Available Resources

📚 references/ - Detailed documentation

• grpc testing
• junit5 migration
• spock patterns
• test setup workflow
• test utilities
• testcontainers setup

---

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