Unit Testing

Purpose

Write effective unit tests using FIRST principles, AAA pattern, test doubles, and TDD. Ensure test quality, maintainability, and meaningful coverage of business logic. This skill covers test architecture, isolation strategies, mock/stub decisions, CI integration, and test suite health monitoring.

Agent Protocol

Trigger

User mentions unit testing, test doubles, mocking, stubbing, TDD, FIRST principles, code coverage, test structure (AAA), or unit test patterns.

Input Context

• Modules or functions under test
• Dependency graph and injection points
• Existing test suite structure
• Coverage targets and CI constraints
• Language and test framework in use

Output Artifact

Unit test suite with proper isolation, test doubles, and CI integration.