AbstractError + CustomError

AbstractError.js

// @see https://github.com/bjyoungblood/es6-error
// @see http://dailyjs.com/2014/01/30/exception-error/
import {map} from 'lodash';

const defineProperty = (obj, prop, value) => {
	Object.defineProperty(obj, prop, {
		configurable: true,
		enumerable: false,
		value
	});
};

class AbstractError {
  constructor(message, props = {}) {
    Error.call(this);
    Error.captureStackTrace(this, this.constructor);
		defineProperty(this, 'message', message);
		defineProperty(this, 'name', this.constructor.name);
		let propertyDefiner = (value, prop) => {
			defineProperty(this, prop, value)
		};
		map(
			props,
			propertyDefiner.bind(this)
		);
  }

	// NOTE: override toString in subclass for more complex formatting
	toString() {
		return `[${this.name}: ${this.message}]`;
	}
}

CustomError.js

class CustomError extends AbstractError {

  constructor(message, code) {
    super(message, {code});
  }

  toString() {
    return `{ [${this.name}: ${this.message}],\n code: '${this.code}' }`;
  }
}

test.js

expect(err).to.be.an.instanceof(CustomError)