How to mock PrismaService for e2e in NestJs? - jestjs

Question

I'm usign nestjs-prisma in NestJs and I have in the following import for the prisma module in the app.module, so in every service I can use the PrismaService as the library allows it.
app.module.ts
import { Module } from '#nestjs/common';
import { PrismaModule } from 'nestjs-prisma';
import { CategoryModule } from './category/category.module';
#Module({
imports: [PrismaModule.forRoot({ isGlobal: true }), CategoryModule],
})
export class AppModule {}
I want to do a e2e test just for the CategoryModule and need to mock the PrismaService, how can i do that?

Answer 1

You need to mook first of all the PrismaModule and then import in it the PrismaService, here is an example.
category.e2e-spec.ts
import { Test, TestingModule } from '#nestjs/testing';
import { INestApplication } from '#nestjs/common';
import * as request from 'supertest';
import { PrismaModule, PrismaService } from 'nestjs-prisma';
import { CategoryModule } from '../src/category/category.module';
describe('CategoryModule (e2e)', () => {
let app: INestApplication;
beforeEach(async () => {
// Here you have to mock the category funtions that you'll use
const mockPrismaService = {
provide: PrismaService,
useFactory: () => ({
category: {
findMany: jest.fn(() => [])
},
}),
};
// Here is the creation of the module and the definition for the service
const mockPrismaModule = {
module: PrismaModule,
providers: [mockPrismaService],
global: true,
};
const moduleFixture: TestingModule = await Test.createTestingModule({
imports: [CategoryModule, mockPrismaModule], // Here is the import for the mock module
}).compile();
app = moduleFixture.createNestApplication();
await app.init();
});
it('(GET) /category', () => {
return request(app.getHttpServer()).get('/category').expect(200);
});
});