Test config with typescript and mongodb-Memory-Server

First install these packages.

npm i --save-dev @types/jest jest @types/supertest supertest ts-jest mongodb-memory-server

Then write test script in package.json scripts section

"test": "jest --watchAll --no-cache"

Then write this script in outside the scripts section

"jest": {
"preset": "ts-jest",
"testEnvironment": "node",
"setupFilesAfterEnv": [
"./src/test/setup.ts"
]
},

create test folder and in there create setup.ts file

import { MongoMemoryServer } from "mongodb-memory-server";
import mongoose from "mongoose";
let mongo: any;

beforeAll(async () => {
mongo = await MongoMemoryServer.create();
const mongoUri = mongo.getUri();
await mongoose.connect(mongoUri);
});

beforeEach(async () => {
jest.clearAllMocks();
const collections = await mongoose.connection.db.collections();
for (let collection of collections) {
await collection.deleteMany({});
}
});

afterAll(async () => {
await mongo.stop();
await mongoose.connection.close();
});