jest-prisma

Jest environment for Prisma integrated testing. You can run each test case in isolated transaction which is rolled back automatically.

How to use

Install

$ npm i @quramy/jest-prisma -D

Configure Jest

/* jest.config.mjs */
export default {
  // ... Your jest configuration

  testEnvironment: "@quramy/jest-prisma/environment",
};

Configure TypeScript

/* tsconfig.json */

{
  "compilerOptions": {
    "types": ["@types/jest", "@quramy/jest-prisma"],
  }
}

Configure Prisma

jest-prisma uses Prisma interactive transaction feature. Edit your schema.prisma and turn interactiveTransactions on.

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["interactiveTransactions"]
}

Write tests

Global object jestPrisma is provided within jest-prisma environment. And Prisma client instance is available via jestPrisma.client

describe(UserService, () => {
  // jestPrisma.client works with transaction rolled-back automatically after each test case end.
  const prisma = jestPrisma.client;

  test("Add user", async () => {
    const createdUser = await prisma.user.create({
      data: {
        id: "001",
        name: "quramy",
      },
    });

    expect(
      await prisma.user.findFirst({
        where: {
          name: "quramy",
        },
      }),
    ).toStrictEqual(createdUser);
  });

  test("Count user", async () => {
    expect(await prisma.user.count()).toBe(0);
  });
});

Configuration

You can pass some options using testEnvironmentOptions.

/* jest.config.mjs */
export default {
  testEnvironment: "@quramy/jest-prisma/environment",
  testEnvironmentOptions: {
    verboseQuery: true,
  },
};

Alternatively, you can use @jest-environment-options pragma in your test file:

/**
 *
 * @jest-environment-options: { "verboseQuery": true }
 *
 */
test("it should execute prisma client", () => {
  /* .... */
});

Tips

Singleton

If your project uses singleton Prisma client instance, such as:

/* src/client.ts */
import { PrismaClient } from "@prisma/client";

export const prisma = new PrismaClient();

/* src/userService.ts */

import { prisma } from "./client.ts";

export function findUserById(id: string) {
  const result = await prisma.user.findUnique({
    where: { id },
  });
  return result;
}

You can replace the singleton instance to jestPrisma.client via jest.mock.

/* setup-prisma.js */

jest.mock("./src/client", () => {
  return {
    prisma: jestPrisma.client,
  };
});

/* jest.config.mjs */
export default {
  testEnvironment: "@quramy/jest-prisma/environment",
  setupFilesAfterEnv: ["<rootDir>/setup-prisma.js"],
};

import { prisma } from "./client";

import { findUserById } from "./userService";

describe("findUserById", () => {
  beforeEach(async () => {
    await prisma.user.create({
      data: {
        id: "test_user_id",
      },
    });
  });

  it("should return user", async () => {
    await findUserById("test_user_id");
    // assertion
  });
});

References

`global.jestPrisma`

export interface JestPrisma {
  /**
   *
   * Primsa Client Instance whose transaction are isolated for each test case.
   * And this transaction is rolled back automatically after each test case.
   *
   */
  readonly client: PrismaClient;
}

Environment options

export interface JestPrismaEnvironmentOptions {
  /**
   *
   * If set true, each transaction is not rolled back but committed.
   *
   */
  readonly disableRollback?: boolean;

  /**
   *
   * Display SQL queries in test cases to STDOUT.
   *
   */
  readonly verboseQuery?: boolean;
}

License

MIT

neet / jest-prisma