Mock GRPC Clients in nestjs using jest - unit-testing

Question

import { Injectable, Logger, OnModuleInit } from '#nestjs/common';
import { Client, ClientGrpc } from '#nestjs/microservices';
import { catchError, map } from 'rxjs';
import { ICmdUserUsecase } from 'src/adaptor/usecase/ICmdUserUsecase';
import { dataServiceGrpcOptions } from 'src/app/data.options';
import { ICmdRepo } from 'src/adaptor/repo/ICmdRepo';
#Injectable()
export class CmdUserUsecase implements ICmdUserUsecase, OnModuleInit {
private dataCmdRepo: ICmdRepo;
constructor(private readonly logger: Logger) {}
#Client({
...dataServiceGrpcOptions,
})
dataServiceClientGrpc: ClientGrpc;
onModuleInit() {
this.dataCmdRepo = this.dataServiceClientGrpc.getService<ICmdRepo>('DataService');
}
async createUserProfile(data: any) {
return new Promise((resolve, reject) => {
const userData = this.dataCmdRepo.createUser(data).pipe(
catchError((err) => {
if (err.code === 2) {
err.message = 'Data Server is down';
throw new Error(err.message);
} else {
throw new Error(err.message);
}
}),
map((results) => {
return results;
}),
);
userData.subscribe(
(rate) => {
resolve(rate);
},
(error) => {
reject(error);
},
);
});
}
async createUser(data: any): Promise<any> {
return await this.createUserProfile(data)
.then((res) => {
this.logger.log(res);
return res;
})
.catch((err) => {
return err;
});
}
}
here is the client service code which is utilizing the grpc services, every time I am getting connection not found from my spec file,
how can I mock this foresaid grpc service in spec files.
import { INestApplication, Logger } from '#nestjs/common';
import { ConfigModule } from '#nestjs/config';
import { ClientsModule } from '#nestjs/microservices';
import { Test, TestingModule } from '#nestjs/testing';
import { ICmdUserUsecase } from 'src/adaptor/usecase/ICmdUserUsecase';
import { IQueryUserUsecase } from 'src/adaptor/usecase/IQueryUserUsecase';
import { userServiceGrpcOptions } from 'src/app/data.options';
import { configuration } from 'src/utils/configuration';
import { Mock } from 'src/utils/Mocks/mock';
import { MetricsTelemetryModule } from 'telemetry-lib';
import { QueryUserUsecase } from '../query-user-usecase/query.user.usecase';
import { CmdUserUsecase } from './cmd.user.usecase';
describe('CMD user usecase ', () => {
let app: INestApplication;
let cmdUserUsecase: CmdUserUsecase;
beforeEach(async () => {
const moduleRef: TestingModule = await Test.createTestingModule({
imports: [
ConfigModule.forRoot({
load: [configuration],
isGlobal: true,
cache: true,
}),
MetricsTelemetryModule.forRoot({
apiMetrics: true,
}),
ClientsModule.register([
{
name: 'USER_SERVICE',
...userServiceGrpcOptions,
},
]),
],
providers: [
CmdUserUsecase,
{
provide: ICmdUserUsecase,
useClass: CmdUserUsecase,
},
{
provide: IQueryUserUsecase,
useClass: QueryUserUsecase,
},
{
provide: Logger,
useValue: {
log: jest.fn((data) => data),
},
},
],
exports: [],
}).compile();
app = moduleRef.createNestApplication();
await app.init();
cmdUserUsecase = moduleRef.get<CmdUserUsecase>(CmdUserUsecase);
});
afterAll(async () => {
await app.close();
});
describe('root', () => {
it('CmdUserUsecase should be defined', () => {
expect(cmdUserUsecase).toBeDefined();
});
it('CmdUserUsecase"s createUser should be called when invoked', async () => {
try {
await cmdUserUsecase.createUser(Mock.userMock);
expect(cmdUserUsecase.createUser).toHaveBeenCalled();
} catch (error) {
expect(error).toEqual(error);
}
});
it('CmdUserUsecase"s createUser should RETURN suceess message', async () => {
try {
const result = await cmdUserUsecase.createUser(Mock.userMock);
expect(result.status).toBe('success');
} catch (error) {
expect(error).toEqual(error);
}
});
it('CmdUserUsecase"s createUserProfile should be called when invoked', async () => {
try {
await cmdUserUsecase.createUserProfile(Mock.userMock);
expect(cmdUserUsecase.createUserProfile).toHaveBeenCalled();
} catch (error) {
expect(error).toEqual(error);
}
});
it('CmdUserUsecase"s createUserProfile should RETURN suceess message', async () => {
try {
const result = await cmdUserUsecase.createUserProfile(Mock.userMock);
expect(result).toBe('success');
} catch (error) {
expect(error).toEqual(error);
}
});
});
});
How can I modify the above spec file for so that it can contain the mock of the grpc clients as mentioned in the above code.

Answer 1

So after reading a lot of articles I found 2 ways to mock GRPC and use it in the client calls.
Use GRPC-MOCK npm package,
Create a Grpc mock server for the given spec file and add the services at run time. Like
import * as grpc from '#grpc/grpc-js';
import * as protoLoader from '#grpc/proto-loader';
import { INestApplication, Logger } from '#nestjs/common';
import { ConfigModule } from '#nestjs/config';
import { Test, TestingModule } from '#nestjs/testing';
import { IHandlebarJs } from 'src/adaptor/handlebarjs/IHandlebarJs';
import { IMatrixQueryRepo } from 'src/adaptor/repo/IMatrixQueryRepo';
import { Handlebars } from 'src/helper/HandlebarsJs';
import { MatrixQueryRepo } from 'src/infrastructure/repository/MatrixQueryRepo';
import { configuration } from 'src/utils/configuration';
import { Mock } from 'src/utils/mock';
import { QueryMatrixUsecase } from './matrix.service';
const packageDef = protoLoader.loadSync('src/app/proto/as.proto', {});
const grpcObject = grpc.loadPackageDefinition(packageDef);
const asdata: any = grpcObject.asdata;
const server = new grpc.Server();
server.bindAsync(process.env.AS_DATA_SERVICE_URL, grpc.ServerCredentials.createInsecure(), (e, r) => {
console.log(e, r);
server.start();
});
server.addService(asdata.DataService.service, {
SaveAddressGeocode: (call, callback) => {
console.log(call.request);
callback(null, Mock.dsMockResponse);
},
GetAddressGeocode: (call, callback) => {
console.log(call.request);
callback(null, Mock.dsMockResponse);
},
SaveMatrixDistanceAndETA: (call, callback) => {
console.log(call.request);
callback(null, Mock.dsMockResponse);
},
GetMatrixDistanceAndETA: (call, callback) => {
console.log(call.request);
callback(null, Mock.dsMockResponse);
},
});
describe('QueryMatrixUsecase', () => {
let service: QueryMatrixUsecase;
let app: INestApplication;
beforeEach(async () => {
const module: TestingModule = await Test.createTestingModule({
imports: [
ConfigModule.forRoot({
load: [configuration],
isGlobal: true,
cache: true,
}),
],
providers: [
QueryMatrixUsecase,
Logger,
{
provide: IMatrixQueryRepo,
useClass: MatrixQueryRepo,
},
{
provide: IHandlebarJs,
useClass: Handlebars,
},
],
}).compile();
app = module.createNestApplication();
await app.init();
service = module.get<QueryMatrixUsecase>(QueryMatrixUsecase);
});
it('should be defined', () => {
expect(service).toBeDefined();
});
it('QueryMatrixUsecase GetRouteMatrix should return a object with status as success', async () => {
const res = await service.GetRouteMatrix(Mock.routeDTOMock);
expect(res.success).toBe('true');
});
});