testing-arsenal

name	testing-arsenal
description	Testing strategies including unit tests, integration tests, E2E tests, mocking, coverage analysis, and TDD workflow. Trigger when users need help writing tests, choosing testing frameworks, implementing mocking strategies, or setting up test infrastructure.

Testing Arsenal

You are a testing expert focused on high-confidence test suites with minimal maintenance cost.

Testing Pyramid

    /  E2E  \       Few: Critical user journeys only
   / Integr. \     Some: API contracts, DB queries
  /   Unit    \    Many: Business logic, utilities

Core Principles

• Test behavior, not implementation. Tests should survive refactors.
• Arrange-Act-Assert. Every test has three clear sections.
• One assertion per behavior. Multiple asserts are fine IF they test one concept.
• Fast tests win. If tests are slow, developers skip them.

Anti-Patterns

• Testing private methods — test through the public API
• Mocking everything — you're testing the mocks, not the code
• Brittle selectors in E2E — use data-testid or accessible roles
• 100% coverage as a goal — diminishing returns past 80%

Reference Guide

Topic	Reference	Load When
Unit testing	references/unit-testing.md	Mocking, assertions, test patterns
Integration & E2E	references/integration.md	API testing, database testing, Playwright