Testing Engineering
Unit, integration, snapshot, contract, fuzz and LLM evals — designing tests that catch real regressions without breaking the bank.
9 articlesin Testing Engineering
Mocking Patterns: Stubs, Spies, Fakes, and When Not to Mock
Master test double patterns — distinguish stubs from mocks, use Vitest module mocking, implement MSW for HTTP, and avoid over-mocking that hides real bugs.
Test Architecture Strategy: Pyramid, Trophy, and CI Optimization
Design a scalable test architecture — apply the test pyramid and testing trophy, set meaningful coverage thresholds, and optimise CI pipeline execution time.
Snapshot Testing: When and How to Use toMatchSnapshot
Use snapshot testing effectively — understand inline vs file snapshots, handle dynamic values, avoid snapshot bloat, and know when snapshots add real value.
Contract Testing with Pact: Consumer-Driven Contracts for Microservices
Implement consumer-driven contract testing with Pact and PactFlow — learn pact files, provider verification, can-i-deploy, and bidirectional contracts.
Test-Driven Development: Red-Green-Refactor in Practice
Apply the TDD cycle — Red-Green-Refactor — to drive better software design. Covers triangulation, outside-in TDD, BDD, and working with legacy code.
E2E Testing with Playwright: Auto-Waiting, Page Objects, and Network Interception
Write reliable end-to-end tests with Playwright — leverage auto-waiting, build Page Object Models, intercept network requests, and eliminate flakiness.
Integration Testing with Testcontainers and WebApplicationFactory
Build reliable integration tests using Testcontainers for real databases, WebApplicationFactory for ASP.NET Core, and supertest for Node.js APIs.
Unit Testing Principles: AAA, Isolation, and Test Doubles
Master the foundational principles of unit testing — Arrange-Act-Assert, test isolation, deterministic tests, and test doubles with Vitest and xUnit.
Testing LLM-Powered Features Without Going Broke
Mock strategies, evaluation harnesses, snapshot testing, and cost-aware CI for LLM-integrated applications.