How to write test cases for Prisma Service file?

Question

I am working in a NestJS project and had a question about that.

I'm not that fluent yet in writing unit test cases, I have written some generic ones for my controllers such as users.controller.spec.ts and for the services users.service.spec.ts. I was wondering, how would I go about writing the test file for the prisma.service.spec.ts? I have a prisma.service.ts file that looks like this:

import { PrismaClient } from '@prisma/client';
import { Injectable, OnModuleDestroy, OnModuleInit } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';

@Injectable()
export class PrismaService
  extends PrismaClient
  implements OnModuleInit, OnModuleDestroy
{
  constructor(config: ConfigService) {
    super({
      datasources: {
        db: {
          url: config.get<string>('DATABASE_URL'),
        },
      },
    });
  }

  async onModuleInit() {
    await this.$connect();
  }

  async onModuleDestroy() {
    await this.$disconnect();
  }

  async cleanDatabase() {
    if (process.env.NODE_ENV === 'production') return;
    const models = Reflect.ownKeys(this).filter((key) => key[0] !== '_');

    return Promise.all(models.map((modelKey) => this[modelKey].deleteMany()));
  }
}

And NestJS CLI generates this generic spec.ts file when you create a service that looks like this:

import { Test, TestingModule } from '@nestjs/testing';
import { PrismaService } from './prisma.service';

describe('PrismaService', () => {
  let service: PrismaService;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [PrismaService],
    }).compile();

    service = module.get<PrismaService>(PrismaService);
  });

  it('should be defined', () => {
    expect(service).toBeDefined();
  });
});