testing-automation-expert_skill

Overview

This skill provides production-grade testing strategies and hands-on patterns for building robust, maintainable test ecosystems. It targets Python (pytest) and TypeScript (Jest, Vitest, Playwright) and covers unit, integration, E2E, contract, accessibility, and mutation testing. The guidance is pragmatic: checklists, CI/CD patterns, recommended packages, and anti-patterns to keep suites fast and reliable.

How this skill works

I inspect the project scope and recommend a layered test pyramid, concrete tooling, and directory organization tuned to your stack. I produce actionable artifacts: a test strategy, pre-implementation checklist, fixture and mocking plan, CI test pipeline configuration, and concrete commands/snippets for pytest, Vitest/Jest, Playwright, Pact, and mutation tools. I also flag anti-patterns and provide remediation steps for flaky or slow suites.

When to use it

• Designing a test strategy for a new feature, service, or project
• Setting up or refactoring pytest, Jest, Vitest, or Playwright suites
• Improving test quality: coverage, mutation testing, and flakiness reduction
• Adding contract testing between microservices or API fuzzing from OpenAPI
• Optimizing CI/CD test pipelines: sharding, artifacts, and trace collection

Best practices

• Follow the testing pyramid: many fast unit tests, few E2E tests for critical paths
• Mock at service boundaries only; prefer real dependencies for integration tests using Testcontainers
• Keep unit tests isolated and focused (one behavior per test, AAA pattern)
• Enforce CI on every PR, shard long suites and upload traces/screenshots for failures
• Use mutation testing and property-based tests to surface blindspots, not just coverage numbers

Example use cases

• Create a test plan that defines unit/integration/E2E boundaries and coverage targets
• Refactor flaky fixtures into factory modules and split conftest/root setup
• Add Pact consumer/provider tests to validate microservice contracts before deploy
• Set up Playwright E2E with axe-core for accessibility checks and cross-browser runs
• Introduce mutation testing (mutmut/stryker) and fix surviving mutants