langchain4j-testing-strategies

# LangChain4J Testing Strategies ## Overview Patterns for unit testing with mocks, integration testing with Testcontainers, and end-to-end validation of RAG systems, AI Services, and tool execution. ## When to Use - **Unit testing AI services**: When you need fast, isolated tests for services using LangChain4j AiServices - **Integration testing LangChain4j components**: When testing real ChatModel, EmbeddingModel, or RAG pipelines with Testcontainers - **Mocking AI models**: When you need deterministic responses without calling external APIs - **Testing LLM-based Java applications**: When validating RAG workflows, tool execution, or retrieval chains ## Instructions ### 1. Unit Testing with Mocks Use mock models for fast, isolated testing. See `references/unit-testing.md`. ```java ChatModel mockModel = mock(ChatModel.class); when(mockModel.generate(any(String.class))) .thenReturn(Response.from(AiMessage.from("Mocked response"))); var service = AiServices.builder(AiService.class) .chatModel(mockModel) .build(); ``` ### 2. Configure Testing Dependencies Setup Maven/Gradle dependencies. See `references/testing-dependencies.md`. - `langchain4j-test` - Guardrail assertions - `testcontainers` - Containerized testing - `mockito` - Mock external dependencies - `assertj` - Fluent assertions ### 3. Integration Testing with Testcontainers Test with real services. See `references/integration-testing.md`. ```java @Testcontainers class OllamaIntegrationTes...