Vitest/Jest setup for TS
Install and configure Vitest or Jest for TypeScript projects; write a tiny test and run it.
Vitest/Jest setup for TS is a free TypeScript Academy lesson on CoddyKit — lesson 1 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the TypeScript Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Intro
Goal: Configure Vitest or Jest for TypeScript. You'll install deps, add a config, write one tiny test, and run it.
Install Vitest
Vitest is Vite-native: fast startup, ESM-first, great DX. Install alongside @types/node for globals.
npm install --save-dev vitest @vitest/ui @types/nodeVitest example
Add vitest.config.ts, write a tiny test, and run with npx vitest or npm test script.
// vitest.config.ts
import { defineConfig } from "vitest/config";
export default defineConfig({
test: { globals: true }
});
// src/sum.ts
export const sum = (a: number, b: number) => a + b;
// src/sum.test.ts
import { sum } from "./sum";
import { describe, expect, it } from "vitest";
describe("sum", () => {
it("adds numbers", () => {
expect(sum(2, 3)).toBe(5);
});
});Install Jest
Jest needs a transformer for TS. Use ts-jest to compile tests on the fly.
npm install --save-dev jest ts-jest @types/jest @types/nodeJest example
Set preset: "ts-jest". Jest will run .ts tests without a build step.
// jest.config.js
module.exports = {
preset: "ts-jest",
testEnvironment: "node",
};
// src/sum.test.ts
import { sum } from "./sum";
test("adds numbers", () => {
expect(sum(2, 3)).toBe(5);
});Scripts
Add scripts for a smooth workflow. Use watch mode for fast feedback during development.
// package.json (scripts)
{
"scripts": {
"test": "vitest",
"test:ui": "vitest --ui",
"test:jest": "jest"
}
}Question
Quick check: In a Jest + TS setup, what does ts-jest do?
Recap
Recap: Vitest (Vite-native) and Jest (widely used) both work great with TS. Configure once, then run tests in watch/CI.
Frequently asked questions
Is the “Vitest/Jest setup for TS” lesson free?
Yes — the full text of “Vitest/Jest setup for TS” is free to read here on the web, and the TypeScript Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the TypeScript Academy course, upgrade to CoddyKit PRO.
What will I learn in “Vitest/Jest setup for TS”?
Install and configure Vitest or Jest for TypeScript projects; write a tiny test and run it. You practise TypeScript Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start TypeScript Academy?
No prior experience is required. TypeScript Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 3, so you can start here or from the beginning and move at your own pace.
How long does the “Vitest/Jest setup for TS” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this TypeScript Academy lesson?
Yes. Every TypeScript Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Vitest/Jest setup for TS
- Typing tests & mocks; expectTypeOf
- E2E typing glimpses (Playwright/Cypress)