Run in Transaction test helper - TypeORM

helper.ts

export function createRunInTransactionHelper<T extends BaseEntity>(
  entity: EntityTarget<T>,
  initFn: (tManager: EntityManager, repo: Repository<T>) => Promise<void>,
) {
  return (fn: (repo: Repository<T>) => Promise<void>) => {
    return getConnection().manager.transaction(async (tManager) => {
      const repo = tManager.getRepository<T>(entity);

      await initFn(tManager, repo);
      await fn(repo);

      tManager.queryRunner?.rollbackTransaction();
    });
  };
}

// Example for using above
const runInTransaction = createRunInTransactionHelper<Admin>(
  Admin,
  async (tManager, adminRepo) => {
    await adminRepo.save(adminRepo.create(mockAdmins));
  },
);

// Example inside `test('')` function of jest
await runInTransaction(async (adminRepo) => {
  const admins = await adminRepo.find();
  expect(admins.length).toBeGreaterThanOrEqual(mockAdmins.length);
});