ReferenceError: Cannot access 'jest_mock_extended_1' before initialization

Question

I have the following code.

singleton.ts

import prisma from "../prismaClient";
import { mockDeep, mockReset } from "jest-mock-extended";
import { PrismaClient } from "@prisma/client";
import { DeepMockProxy } from "jest-mock-extended/lib/cjs/Mock";

jest.mock("../prismaClient", () => ({
  __esModule: true,

  default: mockDeep<PrismaClient>(),
}));

beforeEach(() => {
  mockReset(prismaMock);
});

export const prismaMock = prisma as unknown as DeepMockProxy<PrismaClient>;

prismaClient.ts

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient({
  log: [
    {
      emit: "event",
      level: "query",
    },
    {
      emit: "stdout",
      level: "error",
    },
    {
      emit: "stdout",
      level: "info",
    },
    {
      emit: "stdout",
      level: "warn",
    },
  ],
});

export default prisma;

I am following prisma's guide to unit testing here: https://www.prisma.io/docs/guides/testing/unit-testing. I don't know why I keep getting this error:

This the error message ReferenceError: Cannot access 'jest_mock_extended_1' before initialization

       7 |   __esModule: true,
       8 |
    >  9 |   default: mockDeep<PrismaClient>(),
         |            ^
      10 | }));
      11 |
      12 | beforeEach(() => {

      at src/utils/testUtils/singleton.ts:9:12
      at Object.<anonymous> (src/utils/testUtils/singleton.ts:1:1)
      at Object.<anonymous> (src/resolvers/functions/user.test.ts:1:1)

Answer 1

It seemed weird to import a class that you are mocking just to export it. So i created deepMock of PrismaClient, added it to the jest.mock and exported the deepMock.

import { PrismaClient } from '@prisma/client'
import { mockDeep, mockReset, DeepMockProxy } from 'jest-mock-extended'

const prismaMock = mockDeep<PrismaClient>();

jest.mock("../prismaClient", () => ({
  __esModule: true,
  default: prismaMock
}));

beforeEach(() => {
  mockReset(prismaMock);
});

export { prismaMock }