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EnvModel: Returns model info in 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​

  • Error Metadata: Ensures validation errors include model and property metadata
  • Model Options: Verifies model name and description are included in errors
  • Property Options: Checks that property descriptions are preserved in error info
  • Validation Details: Confirms validation constraints are detailed in the error

GitHub Reference​

Setup Code​

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({ name: 'model name', description: 'model description' })
class AppEnv {
  @EnvModelProperty({ description: 'option description' })
  @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 model info in error if option of env not set', async () => {
  await expect(
    Test.createTestingModule({
      imports: [AppModule.forRoot({})],
    }).compile(),
  ).rejects.toMatchObject({
    info: {
      modelPropertyOptions: [{ description: 'option description', originalName: 'option' }],
      modelOptions: {
        name: 'model name',
        description: 'model description',
        originalName: 'AppEnv',
      },
      validations: {
        option: { constraints: { isNotEmpty: 'option should not be empty' } },
      },
    },
  });
});

What This Test Does​

  1. Creates an EnvModel with rich metadata (name, description, property description)
  2. Attempts to initialize the module without the required environment variable
  3. Expects validation to fail and checks the error object structure
  4. Verifies the error includes:
    • modelPropertyOptions: Property-level metadata with descriptions
    • modelOptions: Model-level metadata with name and description
    • validations: Detailed validation constraint information

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.