Java Testing Advanced

pluginagentmarketplace/custom-plugin-java

This takes your Java testing beyond the basics with four power tools: Testcontainers for spinning up real Postgres or Kafka instances in Docker, Pact for consumer-driven contract testing between services, PIT for mutation testing that actually validates your test quality, and property-based testing for generating edge cases you wouldn't think of. The Testcontainers examples are solid, showing Spring Boot integration with dynamic properties. Mutation testing is where this gets interesting because it tells you if your tests would catch actual bugs, not just pass with green checkmarks. If you're doing microservices or need real integration tests without mocking everything to death, these techniques will save you from production surprises.

skills.sh installs: 331
GitHub stars: 42
last updated: Aug 21, 2026

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Install

$ npx -y skills add pluginagentmarketplace/custom-plugin-java --skill java-testing-advanced --agent claude-code

Installs into .claude/skills of the current project.

Files

Java Testing Advanced Skill

Advanced testing techniques for comprehensive test coverage.

Overview

This skill covers advanced testing patterns including Testcontainers for integration testing, contract testing with Pact, mutation testing with PIT, and property-based testing.

When to Use This Skill

Use when you need to:

Test with real databases (Testcontainers)
Verify API contracts
Find gaps with mutation testing
Generate test cases automatically

Quick Reference

Testcontainers

@Testcontainers
@SpringBootTest
class OrderRepositoryIT {

    @Container
    static PostgreSQLContainer<?> postgres =
        new PostgreSQLContainer<>("postgres:15")
            .withDatabaseName("test")
            .withUsername("test")
            .withPassword("test");

    @Container
    static KafkaContainer kafka =
        new KafkaContainer(DockerImageName.parse("confluentinc/cp-kafka:7.4.0"));

    @DynamicPropertySource
    static void configure(DynamicPropertyRegistry registry) {
        registry.add("spring.datasource.url", postgres::getJdbcUrl);
        registry.add("spring.kafka.bootstrap-servers", kafka::getBootstrapServers);
    }

SKILL.md on GitHub