Bright Training: Avoiding Mocks and Improving HTTP Request Handling

This repository contains training materials for addressing two common issues in Spring Boot applications:

1. Abuse of mocks in tests - Overuse of mocks can lead to brittle tests that are tightly coupled to implementation details.
2. Reliance on HttpServletRequest and HttpServletResponse in service layers - Direct use of servlet API in service layers makes code harder to test and less reusable.

Training Plan

This repository is organized into branches that demonstrate the progression from problematic code to improved implementations:

Branch 1: initial-state

• Examples of problematic code with excessive mocking
• Examples of service layer code tightly coupled to servlet API
• Tests that are brittle and hard to maintain

Branch 2: refactored-code

• Refactored code using "Testing Without Mocks" patterns
• Improved HTTP request handling with proper abstractions
• Tests that are more robust and less coupled to implementation details

Key Concepts

Testing Without Mocks

Based on James Shore's "Testing Without Mocks: A Pattern Language", this approach focuses on:

• Using real objects instead of mocks when possible
• Creating "Nullables" or "Fakes" for infrastructure dependencies
• Using "Output Trackers" to verify behavior without mocks
• Structuring code to be more testable without mocks

Improved HTTP Request Handling

• Abstracting HTTP request/response details behind interfaces
• Using DTOs to pass data between layers
• Keeping servlet API dependencies at the controller level only

Getting Started

This project uses:

• Java 21
• Spring Boot 3.2.0
• Gradle

To run the application:

./gradlew bootRun

To run the tests:

./gradlew test

Training Sessions

Session 1: Understanding the Problems

• Identify issues with current approach
• Demonstrate how current tests break during refactoring
• Show how servlet API dependencies make testing difficult

Session 2: Implementing Solutions

• Introduce "Testing Without Mocks" patterns
• Refactor code to remove servlet API dependencies from service layer
• Create more robust tests using the new patterns

Session 3: Applying to Real Projects

• Strategies for incrementally improving existing codebases
• Identifying good candidates for refactoring
• Measuring success: fewer test failures during refactoring