EnvModel: Returns error 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're Testing

• Environment Validation: Ensures @IsNotEmpty() decorator on env properties works correctly
• Error Handling: Verifies that missing required environment variables throw proper validation errors
• EnvModel Integration: Tests the integration between EnvModel, EnvModelProperty, and envTransform utility
• Process.env Mapping: Validates that environment variables are read from process.env

GitHub Reference

• File: utils.spec.ts
• Lines: 8-46

Setup Code

The test sets up an environment model with a required field:

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

@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],
        },
      ],
    };
  }
}

Test Code

it('should return error if option of env not set', async () => {
  await expect(
    Test.createTestingModule({
      imports: [AppModule.forRoot({})],
    }).compile(),
  ).rejects.toHaveProperty('errors.0.constraints.isNotEmpty', 'option should not be empty');
});

What This Test Does

1. Creates an EnvModel with a required option field decorated with @IsNotEmpty()
2. Attempts to initialize the module with an empty configuration {}
3. Expects the compilation to fail with a validation error
4. Verifies the error message contains the correct validation constraint: 'option should not be empty'

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.