10_testcontainers_go

Testcontainers-go

Testcontainers is a library for integration testing with real Docker containers. Spin up databases, message queues, or any Docker service for realistic integration tests.

📦 Installation

go get github.com/testcontainers/testcontainers-go

🎯 Features

• Real Services: Test against actual databases, Redis, Kafka, etc.
• Isolated Environment: Each test gets fresh containers
• Auto-Cleanup: Containers removed after tests
• Wait Strategies: Wait for services to be ready
• Network Control: Custom networks and port mapping
• Docker Compose: Support for docker-compose files

📖 Usage

Basic Container

ctx := context.Background()
req := testcontainers.ContainerRequest{
    Image:        "redis:latest",
    ExposedPorts: []string{"6379/tcp"},
    WaitingFor:   wait.ForLog("Ready to accept connections"),
}
container, _ := testcontainers.GenericContainer(ctx, testcontainers.GenericContainerRequest{
    ContainerRequest: req,
    Started:          true,
})
defer container.Terminate(ctx)

🚀 Running Tests

# Requires Docker to be running
docker --version

# Run tests
go test

✅ Pros

• ✅ Test with real services (not mocks)
• ✅ Isolated test environment
• ✅ Reproducible across machines
• ✅ Great for integration/E2E tests
• ✅ Supports many pre-built containers

❌ Cons

• ❌ Requires Docker installation
• ❌ Slower than unit tests
• ❌ Higher resource usage
• ❌ Not suitable for CI without Docker

🔗 Resources

• Official Documentation
• GitHub Repository
• Examples

💡 Best Practices

1. Always defer Terminate(): Clean up containers
2. Use wait strategies: Ensure services are ready
3. Reuse containers: Within test suites when possible
4. Tag tests: Use build tags for integration tests
5. Check Docker: Verify Docker is running before tests