message-builder.js

/**
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

'use strict';
var ErrorMessage = require('../classes/error-message.js');

/**
 * The handler setup function serves to produce a bound instance of the
 * of a factory for ErrorMessage class instances with configuration-supplied
 * service contexts automatically set.
 * @function handlerSetup
 * @param {NormalizedConfigurationVariables} config - the environmental
 *  configuration
 * @returns {ErrorMessage} - a new ErrorMessage instance
 */
function handlerSetup(config) {
  /**
   * The interface for creating new instances of the ErrorMessage class which
   * can be used to send custom payloads to the Error reporting service.
   * @returns {ErrorMessage} - returns a new instance of the ErrorMessage class
   */
  function newMessage() {
    // The API expects a reported error to contain a stack trace.
    // However, users do not need to provide a stack trace for stack
    // traces built using the message builder.  Instead, here we store
    // the stack trace with the parts that reference the error-reporting's
    // internals removed.  Then when the error is reported, the stored
    // stack trace will be appended to the user's message for the error.
    //
    // Note: The stack trace at the point where the user constructed the
    //       error is used instead of the stack trace where the error is
    //       reported to be consistent with the behavior of reporting a
    //       an error when reporting an actual Node.js Error object.
    var fauxError = new Error('');
    var fullStack = fauxError.stack.split('\n');
    var cleanedStack = fullStack.slice(2).join('\n');

    var em = new ErrorMessage().setServiceContext(
                         config.getServiceContext().service,
                         config.getServiceContext().version);
    em._autoGeneratedStackTrace = cleanedStack;
    return em;
  }

  return newMessage;
}

module.exports = handlerSetup;