Real method being called instead of mocked one in Jest test | NestJS | Page 1

blazing laurel May 13, 2023, 7:32 PM

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Attempting here to test the validateUser method of the AuthService service.

However, within the validateUser method, it contains a call to a function within UsersService, named user, which queries the database for a specific user. For the unit test to work without a database connection, I'm overriding this method within the providers array when creating the testing module.

The issue is that the mocked UsersService is not being called - the real method in the real service is the one that is actually being called.

My best guess is that this is something with dependencies - maybe I'm importing incorrectly and that means that the real one is being called? I'm at a loss here. Code is below.

let authService: AuthService;

  beforeEach(async () => {
    const userData = {
      id: 1,
      username: "John",
      email: "[email protected]",
      password: await bcrypt.hash("password", 10),
      verified: true
    };

    const module = await Test.createTestingModule({
      providers: [
        AuthService,
        {
          provide: UsersService,
          useValue: {
            user: jest.fn().mockResolvedValue(userData)
          }
        }
      ],
      imports: [
        AppModule,
        MailModule,
        HttpModule
      ]
    }).compile();

    authService = await module.get(AuthService);
  });

  describe("when validating a user", () => {
    it("should verify a hashed password successfully", async () => {
      const result = await authService.validateUser("", "password");
      expect(result).toBe(true);
    });
  });

vocal panther May 13, 2023, 7:33 PM

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You shouldn't add imports in your unit test, just fyi

blazing laurel May 13, 2023, 7:34 PM

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vocal panther You shouldn't add imports in your unit test, just fyi

I've had to bite my tongue when writing this test. Know it's bad practice, my dependency tree needs to be reworked. Trying to just get the skeleton of the test for this service working before I go around poking anything else.

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I get issues with dependency resolution if I don't import here.

vocal panther May 13, 2023, 7:35 PM

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What all does AuthService need to function?

blazing laurel May 13, 2023, 7:36 PM

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vocal panther What all does `AuthService` need to function?

constructor(
    private readonly usersService: UsersService,
    private readonly jwtService: JwtService,
    private readonly httpService: HttpService,
    private readonly configService: ConfigService,
    @InjectRedis() private readonly redis: Redis
  ) {}

vocal panther May 13, 2023, 7:37 PM

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So something like

providers: [
  AuthService,
  {
    provide:UsersService,
    useValue: userMock,
  },
  {
    provide: JwtService,
    useValue: jwtMock,
  },
  {
    provide: HttpService,
    useVlaue: httpMock,
  },
  {
    provide: ConfigService,
    useVlaue: configMock,
  },
  {
    provide: getRedisToken(), // assuming this exists,
    useValue: redisMock,
  }
]

blazing laurel May 13, 2023, 7:38 PM

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Eventually yes, but I wanted to isolate it to this one test with usersService.

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The validateUser function is only dependent on UsersService.

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Is there anything special I need to do for the mocked UsersService to be the one that is used for this module?

vocal panther May 13, 2023, 7:41 PM

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I'm concerned about the AppMoudle import, because that's probably importing AuthModule which might mean that when you module.get(AuthService) you are getting the "live" version instead of the mocked one

blazing laurel May 13, 2023, 7:42 PM

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I had a suspicion about that too. I temporarily added that in.

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I have a provider named MailConfig within MailModule that sets the configuration for SMTP.

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Without the AppModule import,

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Error: Nest can't resolve dependencies of the MailConfig (?). Please make sure that the argument ConfigService at index [0] is available in the MailModule context.

vocal panther May 13, 2023, 7:44 PM

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Why does MailModule need to be imported?

blazing laurel May 13, 2023, 7:45 PM

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I'm not sure, it was just something that fixed a dependency issue. Was throwing stuff to see what would stick.

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If I limit my imports to just HttpModule, it then throws issues with my JwtModule, which is globally declared in AppModule.

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For example, this compiles dependencies successfully: ```ts
imports: [
AppModule,
HttpModule
]

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With just the HttpModule import, this is then the issue: Error: Nest can't resolve dependencies of the AuthService (UsersService, ?, HttpService, ConfigService, RedisModule:default). Please make sure that the argument JwtService at index [1] is available in the RootTestModule context.

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My JwtModule is globally declared in my AppModule's imports, so it's strange as to why it couldn't find JwtService:

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{
    ...JwtModule.registerAsync({
        useFactory: (configService: ConfigService) => ({
            secret: configService.get("JWT_TOKEN"),
            signOptions: {
                expiresIn: "14d"
            }
        }),
        inject: [ConfigService]
    }),
    global: true
}

vocal panther May 13, 2023, 7:56 PM

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Why not get rid of the AppModule and import the necessary modules to the improts. I mean, I really suggest mocking them out in the first place, but if you're gonna import things why not import smaller things rather than the whole application?

blazing laurel May 13, 2023, 9:44 PM

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vocal panther Why not get rid of the `AppModule` and import the necessary modules to the `impr...

If I have globally declared imports in my AppModule, do I need to recreate them here in the test?

vocal panther May 13, 2023, 9:44 PM

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Again, I would avoid importing the app module in your test, so yes, you'd need to import that global module to the test.

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And I really can't stress enough how much I would avoid imports in unit tests in the first place

blazing laurel May 14, 2023, 12:57 AM

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vocal panther And I really can't stress enough how much I would avoid imports in unit tests in...

Going to heed that advice and move over to your recommendation of providing each dependency of the service.

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Not sure if you would know how, but how would I go about using a decorator for one of the dependencies?

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Redis needs to have a @InjectRedis() attached to it when in the constructor, and it appears that simply using the pure Redis object without anything else in the providers array does not work.

vocal panther May 14, 2023, 2:31 AM

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What's the package you use for redis?

blazing laurel May 14, 2023, 2:32 AM

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Apologies for the ghost ping liao

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IORedis, with the decorator from @ liaoliaots/nestjs-redis

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Found a workaround - you can pass a redisService and then call getClient() on that.

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Didn't realize that was an applicable method, thought the decorator was the only way.

vocal panther May 14, 2023, 2:35 AM

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Try REDIS_CLIENTS imported from that package

blazing laurel May 14, 2023, 2:36 AM

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No need, did it via the way described as the service method here: https://github.com/liaoliaots/nestjs-redis/blob/main/docs/latest/redis.md

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Ended up with my providers array looking like this, no imports needed.

#Real method being called instead of mocked one in Jest test