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EnvModel: Returns option value from service

Overview​

These tests validate nestjs-mod EnvModel: environment variable reading, required field validation, and DI value propagation into services.

What We Do And Verify​

  • We verify how envTransform and EnvModel/EnvModelProperty decorators extract and validate env values.

  • We confirm expected behavior for missing or invalid required env fields.

  • We lock the DI access contract for env values in services.

  • 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, Injectable, Module } from '@nestjs/common';
import { Test, TestingModule } from '@nestjs/testing';
import { IsNotEmpty } from 'class-validator';
import { EnvModel, EnvModelProperty } from './decorators';
import { envTransform } from './utils';

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

  // full test in the block below

});

Test Code​

  it('should return option value from service', async () => {
    @EnvModel()
    class AppEnv {
      @EnvModelProperty()
      @IsNotEmpty()
      option!: string;
    }

    @Injectable()
    class AppService {
      constructor(private readonly appEnv: AppEnv) {}

      getEnv() {
        return this.appEnv;
      }
    }

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

    process.env['OPTION'] = 'value1';

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

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