maestro/src/decorators/shared.ts

import { type CustomDecorator } from '@nestjs/common';

// implementation copied from SetMetadata, but tweaked to get existing values
// of the metadataKey and accumulate it with the new metadataValue
export function SetMultipleMetadata(
  metadataKey,
  metadataValue,
): CustomDecorator {
  const decoratorFactory: CustomDecorator = (target, key?, descriptor?) => {
    // .start: tweak
    // descriptor?.value = function decorator; target = class decorator
    const accumulatedVal =
      Reflect.getMetadata(metadataKey, descriptor?.value ?? target) ?? [];
    accumulatedVal.push(metadataValue);
    // .end: tweak

    if (descriptor) {
      Reflect.defineMetadata(metadataKey, accumulatedVal, descriptor.value);
      return descriptor;
    }

    Reflect.defineMetadata(metadataKey, accumulatedVal, target);
    return target;
  };

  decoratorFactory.KEY = metadataKey;
  return decoratorFactory;
}