override datasource provider to use pg-mem

transactions.e2e-spec.ts

import * as request from 'supertest';
import { Test } from '@nestjs/testing';
import { INestApplication } from '@nestjs/common';
import { DataSource } from 'typeorm';
import { setupDatabase } from '../setup-database';
import { AppModule } from '../../src/app.module';
import { TransactionRepository } from '../../src/transactions/repository/transactions.repository';

describe('TransactionController (e2e)', () => {
  let app: INestApplication;
  let dataSource: DataSource;
  let transactionRepository: TransactionRepository;

  beforeAll(async () => {
    dataSource = await setupDatabase();
    const moduleFixture = await Test.createTestingModule({
      imports: [AppModule],
      providers: [TransactionRepository],
    })
      .overrideProvider(DataSource)
      .useValue(dataSource)
      .compile();

    app = moduleFixture.createNestApplication();
    transactionRepository = moduleFixture.get<TransactionRepository>(
      TransactionRepository,
    );
    await app.init();
  });

});