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ConfigModel: Returns 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​

  • Validation Logic: Ensures @IsNotEmpty() decorator on config properties works correctly
  • Error Handling: Verifies that missing required options throw proper validation errors
  • ConfigModel Integration: Tests the integration between ConfigModel, ConfigModelProperty, and configTransform utility

GitHub Reference​

Setup Code​

The test sets up a configuration model with a required field:

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()
class AppConfig {
  @ConfigModelProperty()
  @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 error if option of config 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 a ConfigModel 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.