When to Apply: Reference when working with Test::Unit in Ruby, preferring classic assert_equal style over RSpec's DSL, or maintaining legacy Ruby test suites. Triggers on "Test::Unit", "assert_equal Ruby", "Ruby test-unit".
Playbook Deep Dive (9 sections): §1 Project Setup · §2 Core Test Patterns · §3 Data-Driven Testing · §4 Mocking & Stubbing · §5 Custom Assertions · §6 Integration Testing · §7 CI/CD Integration · §8 Debugging Table · §9 Best Practices
The agent loads from 2 on-demand reference files (advanced-patterns.md, playbook.md) containing detailed implementation guides, cloud integration patterns, debugging tables, and language-specific best practices.