typed-jest

An all-in-one test framework supporting TypeScript out-of-box.

Features

• 100% compatible with Jest. Use typed-jest just like you would use jest.
• Out-of-the-box TypeScript support.
• All in one. The best practice to use jest in TypeScript (CJS) project.
• No implicit globals.
• Sensible defaults adhering to best practices. Most projects work seamlessly with zero configuration.
• Integrated supertest in it.

Why

This is an all-in-one test framework designed for legacy CommonJS TypesScript project, supporting experimentalDecorators and emitDecoratorMetadata. For modern ESM project, you should consider to use Vitest.

Usage

1. Uninstall jest, @types/jest, and ts-jest if they are already installed in your project.

pnpm remove jest @types/jest ts-jest

2. Install typed-jest.

pnpm add -D typed-jest

3. Create an app.ts file.

import fs from "node:fs";
import express, { type Express } from "express";

const json = fs.readFileSync("package.json", "utf-8");

const app: Express = express();
app.get("/pkg", function (_req, res) {
  console.log("package.json", json);
  res.status(200).json(JSON.parse(json));
});

export default app;

4. Create an app.spec.ts file.

import { afterEach, beforeEach, describe, expect, it, jest } from "typed-jest";
import supertest from "typed-jest/supertest";
import app from "./app";

jest.mock("node:fs", () => ({
  readFileSync: () => JSON.stringify({ foo: "bar" }),
}));

describe("app", () => {
  beforeEach(() => {
    console.log("========beforeEach running========");
  });
  afterEach(() => {
    console.log("========afterEach running========");
  });
  it("should be 2", () => {
    expect(1 + 1).toBe(2);
  });
  it("should success", async () => {
    const response = await supertest(app).get("/pkg");
    expect(response.status).toEqual(200);
    expect(response.body).toStrictEqual({ foo: "bar" });
  });
});

5. Run pnpm jest to execute tests.

Note: For the projects using npm as its package manager, please use npx typed-jest instead.

Configuration

1. Add more CLI configurations after the pnpm jest command. For example, run pnpm jest --coverage to collect test coverage. Run pnpm jest -h for more CLI options information.
2. Add a jest.config.js file in the root of your project. Consult the official Jest documentation for more information.

How it works

If you don't include CLI options when running pnpm jest, we will append some sensible defaults:

• --transform='{"^.+\\\\.tsx?$":"ts-jest"}': This option transforms TypeScript files, so you can support TypeScript projects without additional configurations or installations.
• --passWithNoTests: This option prevents the CLI from producing errors if no tests are found. You can override this default by pnpm jest --passWithNoTests=false.
• --collectCoverageFrom='**/src/**/*.{js,mjs,cjs,jsx,ts,mts,cts,tsx}': This option specifies the location for collecting test coverage. Override it as needed: pnpm jest --collectCoverageFrom='**/lib/**/*.js'

License

MIT