TypeScript
TypeScript types are part of your API surface — a change to a generic utility or function signature can break callers without touching any runtime behavior. Type-level tests catch these regressions. Tools like tsd, expect-type, and @vitest/expect-type let you assert that expressions have specific types, that certain type combinations are
Angular
Angular component tests use TestBed to mount a component in a real Angular environment, then query the DOM to assert on rendered output and trigger user interactions. This guide covers the full component testing API: querying the DOM, testing @Input bindings, asserting on @Output events, handling ChangeDetectionStrategy.OnPush, and testing
Flutter
Flutter widget tests mount a widget in a test environment — no device or emulator needed. The WidgetTester API gives you control over the widget tree: find elements by text, key, or type; tap, drag, and enter text; advance the clock; and assert on the rendered output. This guide covers the
Vue.js
Vue Test Utils 2 is the official testing library for Vue 3 components. It mounts components in a virtual DOM (or real browser with Cypress), lets you interact with them, and provides a rich API for asserting on rendered output, emitted events, and DOM structure. This guide covers the full
Angular
TestBed is Angular's testing module — it creates a mini Angular application for each test suite, complete with dependency injection, component compilation, and the Angular zone. Understanding how to configure TestBed, provide mock services, and control async execution is the foundation of effective Angular testing. This guide goes deep
TypeScript
ts-jest is a Jest transformer that lets you run TypeScript tests without a separate compile step. It integrates with your existing tsconfig, supports path aliases via moduleNameMapper, and provides typed mock utilities. This guide covers everything from initial setup to advanced configuration including monorepo path aliases, module mocking patterns, and
Flutter
Flutter ships with three testing layers built into the SDK: unit tests (dart:test) for pure Dart logic, widget tests (flutter_test) for individual Flutter widgets in isolation, and integration tests (integration_test) for full app flows on a real device or emulator. This guide covers all three — setup, writing
Vue.js
Vue.js testing covers three levels: unit tests for composables and utilities, component tests for Vue components with Vue Test Utils 2, and end-to-end tests with Cypress or Playwright. The recommended stack for Vue 3 projects is Vitest for unit and component tests (it integrates directly with Vite) plus Cypress
Angular
Angular ships with a complete testing setup: Jasmine as the test framework, Karma as the test runner, and TestBed as the Angular testing module that lets you configure and instantiate components and services the same way the Angular runtime does. For E2E tests, the Angular team now recommends Playwright over
TypeScript
TypeScript testing requires one extra layer beyond JavaScript testing: your test runner must understand TypeScript. The two main approaches are ts-jest (for Jest-based projects) and Vitest (for Vite-based projects). This guide covers setting up both, configuring tsconfig correctly for tests, writing type-safe tests, and avoiding the most common TypeScript testing
Tools & Frameworks
xUnit.net is the most modern .NET testing framework, favored by Microsoft's own teams and the open-source community. It's the default choice for new .NET projects. This guide covers installation, writing Facts and Theories, using assertions, mocking dependencies, async testing, and running tests in CI pipelines.
Go
Table-driven tests are Go's idiomatic approach to testing multiple input/output combinations. Instead of writing one test function per case, you define all cases as a slice of structs and loop through them. The Go standard library itself uses this pattern extensively. The Basic Pattern func TestAdd(t