#Testing

TDD and BDD both share a 'tests first' philosophy but differ in focus and application. From the Red-Green-Refactor cycle to Gherkin syntax — a practical TypeScript comparison.

I've wasted hours with direct fetch mocks or vi.mock() on axios, only to find the mock drifted from the real API. MSW intercepts at the network level and eliminates that problem. Here's everything from setup to Vitest and Storybook integration.

Unit tests all green, but QA finds a bug in three clicks. That's the E2E gap. Here's everything you need to automate real browser scenarios with Playwright — from first test to CI integration.

Frontend development blocked by unfinished APIs. MSW intercepts requests at the network level so you can build and test without a real backend.

Spent a whole night debugging because I confused vi.mock() and vi.spyOn(). Here's a practical deep dive into Vitest's advanced features — mocking strategies, snapshot testing, and why your coverage numbers might be lying to you.

Editing a modal inside a dashboard requires 5 clicks to see changes? Isolate your UI with Storybook and develop components 10x faster.

I achieved 100% test coverage, but production crashed immediately. The culprit? Overusing 'fake objects'. I share my failure story caused by confusing Mocks, Stubs, and Spies, and explain the correct way to use Test Doubles.

I was once obsessed with reaching 100% test coverage. After lighting up every line green, I deployed with confidence, only to face a critical bug. I discuss what coverage doesn't tell you, the dangers of meaningless tests, and the true metric of test quality.

Differences and usage of test types

Writing test BEFORE code. Red -> Green -> Refactor. The Double-Entry Bookkeeping of Programming.

Unit tests check the bricks; E2E tests check the building. Learn how to simulate real user journeys using modern tools like Cypress and Playwright. We cover best practices for writing resilient selectors, handling authentication, fighting test flakiness, and where E2E fits in the Testing Pyramid.

'It works on my machine' is no longer an excuse. Robots test (CI) and deploy (CD) when you push code. Deploy 100 times a day with automation pipelines.