EnvModel: Returns error message if option of env not set

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

• File: utils.spec.ts
• Line: 48

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 error message if option of env not set', async () => {
    try {
      @EnvModel()
      class AppEnv {
        @EnvModelProperty()
        @IsNotEmpty()
        option!: string;
      }

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

      await Test.createTestingModule({
        imports: [AppModule.forRoot({})],
      }).compile();
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
    } catch (err: any) {
      expect(err.message).toEqual(`obj['option'],process.env['OPTION']-isNotEmpty`);
    }
  });