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ConfigModel: Returns model info in error if option of config not set

Overview​

These tests validate nestjs-mod ConfigModel: configuration transformation, input validation, and error contract on invalid parameters.

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​

The test creates a ConfigModel with detailed metadata:

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

@ConfigModel({ name: 'model name', description: 'model description' })
class AppConfig {
  @ConfigModelProperty({ description: 'option description' })
  @IsNotEmpty()
  option!: string;
}

@Module({ providers: [AppConfig] })
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],
        },
      ],
    };
  }
}

Test Code​

it('should return model info in error if option of config 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: 'AppConfig',
      },
      validations: {
        option: { constraints: { isNotEmpty: 'option should not be empty' } },
      },
    },
  });
});

What This Test Does​

  1. Creates a ConfigModel with rich metadata (name, description, property description)
  2. Attempts to initialize the module with an empty configuration
  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.