Testing TDDStudy Notes

Arrange-Act-Assert Pattern

Master the three-phase structure - Arrange, Act, Assert - that keeps unit tests readable, focused, and easy to debug when they fail.

Assertion Styles and Best Practices

Compare classic, fluent, and matcher-based assertion styles and learn practical rules for writing assertions that fail with useful messages.

Choosing a Testing Framework

How to evaluate and select a testing framework based on language fit, assertion style, runner speed, and team workflow.

Code Review and Testing Culture

How code review practices reinforce (or undermine) a team's testing discipline, and how to build a healthy testing culture.

Common TDD Pitfalls

Recognize the most frequent ways teams misapply TDD — testing internals, skipping red, and overmocking — and how to avoid each.

Continuous Testing in CI/CD

Learn how to design a test pipeline - from fast unit tests to slower integration and end-to-end suites - that gives developers fast, reliable feedback inside a…

Contract Testing Explained

Understand how contract testing verifies that independently-deployed services agree on the shape of their API, catching integration breakage without full end-t…

End-to-End Testing Basics

Understand what end-to-end (E2E) tests are, when they earn their cost, and how to write a stable, meaningful E2E suite without it becoming slow and brittle.

Flaky Tests and How to Fix Them

Learn what makes automated tests flaky, how to systematically diagnose the root cause, and proven techniques to make your test suite deterministic and trustwor…

Parameterized Tests

Learn how to replace repetitive, copy-pasted test cases with data-driven parameterized tests that scale to cover many inputs cleanly.

Refactoring Safely with Tests

Understand why a solid test suite is what makes structural code changes safe, and how to build one for legacy code that has none.

TDD Case Study Walkthrough

A step-by-step worked example of building a small feature using the red-green-refactor TDD cycle.

TDD for a Simple Feature

Walk through a complete red-green-refactor cycle for a realistic feature, from the first failing test to a clean, general implementation.

TDD vs BDD

Compare test-driven and behavior-driven development: what BDD adds on top of TDD, when each fits best, and how their tooling differs.

Test Coverage Explained

Understand how line, branch, and path coverage are measured, why 100% coverage doesn't guarantee correctness, and how to use coverage reports wisely.

Test Doubles: Mocks, Stubs, and Fakes

Understand the different kinds of test doubles — dummies, stubs, spies, mocks, and fakes — and when to reach for each one.

Test-Driven Development Explained

Learn what TDD actually is, how the write-test-first workflow changes design and confidence, and where it fits alongside other testing practices.

Test Isolation and Independence

Understand why each test must run independently of every other test, and the patterns - fresh fixtures, dependency injection, and cleanup - that guarantee it.

Testing APIs and Databases

Learn practical techniques for testing HTTP APIs and the databases behind them, including request assertions, schema validation, and reliable data setup.

Testing Interview Questions

Common technical interview questions on testing and TDD, with the reasoning behind strong answers.

Testing Legacy Code

Learn practical techniques - characterization tests, seams, and incremental refactoring - for safely adding automated tests to code that has none.

Testing Quick Reference

A condensed reference of core testing terminology, patterns, and rules of thumb for day-to-day use.

Testing with a Real Browser

Learn how browser automation tools like Playwright and Cypress drive a real, rendered browser to test frontend behavior the way actual users experience it.

The Red-Green-Refactor Cycle

A deep dive into the three-step heartbeat of TDD -- writing a failing test, making it pass with minimal code, then refactoring safely.