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