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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 Do And Verify​

  • We verify how configTransform and ConfigModel/ConfigModelProperty decorators process input parameters.

  • We lock the validation contract and error shape expected by configuration consumers.

  • We confirm that modules/services receive properly prepared configuration values.

  • We explicitly validate the error contract: not only failure itself, but also error shape/content expected by module consumers.

GitHub Reference​

Setup Code​

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

describe('Config model: Utils', () => {

  // full test in the block below

});

Test Code​

  it('should return option value from service', async () => {
    @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],
            },
          ],
        };
      }
    }

    const moduleRef: TestingModule = await Test.createTestingModule({
      imports: [AppModule.forRoot({ option: 'value1' })],
    }).compile();
    const appService = moduleRef.get(AppService);

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