Example of auto-rollback transactions with Mikro-Orm for testing

integration.test.ts

import {
  Connection,
  EntityManager,
  IDatabaseDriver,
  MikroORM,
} from "@mikro-orm/core";
import { PostgreSqlDriver } from "@mikro-orm/postgresql";

import { getConfig } from "../config";
import { UserEntity } from "../entities";

type TxOptions<T extends IDatabaseDriver<Connection>> = {
  em: EntityManager<T>;
  inner: (em: EntityManager<T>) => Promise<void>;
  outer: (em: EntityManager<T>) => Promise<void>;
};

const tx = async <T extends IDatabaseDriver<Connection>>({
  em,
  inner: cbInner,
  outer: cbOuter = () => Promise.resolve(),
}: TxOptions<T>) => {
  const rollback = Symbol("rollback");
  try {
    await em.transactional(async (emOuter) => {
      await emOuter.transactional(async (emInner) => {
        await cbInner(emInner as EntityManager<T>);
      });
      await cbOuter(emOuter as EntityManager<T>);
      throw rollback;
    });
  } catch (e) {
    if (e !== rollback) {
      throw e;
    }
  }
};

describe("create user in inner transaction, find it in outer transaction, and rollback to an empty db", () => {
  const config = getConfig();
  let orm: MikroORM<PostgreSqlDriver>;

  beforeAll(async () => {
    orm = await MikroORM.init(config);
  });

  afterAll(async () => {
    await orm.close();
  });

  it("should create a user", async () => {
    const user = new UserEntity({
      emailAddress: "[email protected]",
    });

    await tx({
      em: orm.em,
      inner: async (em) => {
        const userRepository = em.getRepository(UserEntity);
        userRepository.persist(user);
      },
      outer: async (em) => {
        const retrieved = await em
          .getRepository(UserEntity)
          .findOneOrFail(user.id);
        expect(retrieved).toEqual(user);
      },
    });
  });
});