ConfigModel: Returns option value from service

Overview

These tests validate nestjs-mod ConfigModel: configuration transformation, input validation, and error contract on invalid parameters.

What We're Testing

• Dependency Injection: Ensures ConfigModel is properly injected into services
• Configuration Assignment: Verifies provided config values are set on the model instance
• Service Integration: Tests that services can access configuration through injected models
• configTransform Integration: Confirms the transform utility properly processes config data

GitHub Reference

• File: utils.spec.ts
• Lines: 102-150

Setup Code

The test creates a ConfigModel, a service that uses it, and a module that provides both:

import { DynamicModule, Injectable, Module } from '@nestjs/common';
import { Test, TestingModule } from '@nestjs/testing';
import { IsNotEmpty } from 'class-validator';
import { ConfigModel, ConfigModelProperty } from './decorators';
import { configTransform } from './utils';

@ConfigModel()
class AppConfig {
  @ConfigModelProperty()
  @IsNotEmpty()
  option!: string;
}

@Injectable()
class AppService {
  constructor(private readonly appConfig: AppConfig) {}

  getConfig() {
    return this.appConfig;
  }
}

@Module({ providers: [AppConfig, AppService] })
class AppModule {
  static forRoot(config: Partial<AppConfig>): DynamicModule {
    return {
      module: AppModule,
      providers: [
        {
          provide: `${AppConfig.name}_loader`,
          useFactory: async (emptyAppConfig: AppConfig) => {
            if (config.constructor !== Object) {
              Object.setPrototypeOf(emptyAppConfig, config);
            }
            const obj = await configTransform({
              model: AppConfig,
              data: config,
            });
            Object.assign(emptyAppConfig, obj.data);
          },
          inject: [AppConfig],
        },
      ],
    };
  }
}

Test Code

it('should return option value from service', async () => {
  const moduleRef: TestingModule = await Test.createTestingModule({
    imports: [AppModule.forRoot({ option: 'value1' })],
  }).compile();
  const appService = moduleRef.get(AppService);

  expect(appService.getConfig()).toMatchObject({ option: 'value1' });
});

What This Test Does

1. Creates a ConfigModel with a required option field
2. Creates a service that injects the ConfigModel and provides a getter
3. Initializes the module with configuration { option: 'value1' }
4. Compiles the testing module successfully (validation passes)
5. Retrieves the service from the module container
6. Verifies the service returns the correct configuration value through getConfig()

Key Points

• This test locks the behavior contract of the target nestjs-mod block in this scenario.
• Assertions protect integration boundaries and reduce regression risk when internals evolve.