dukeswag/test/helpers.js

/****************************************************************************
 Copyright 2015 Apigee Corporation

 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 fs = require('fs');
var _ = require('lodash');
var util = require('util');

module.exports.copyFile = function(source, target, cb) {
  cb = _.once(cb);

  var rd = fs.createReadStream(source);
  rd.on('error', function(err) {
    cb(err);
  });

  var wr = fs.createWriteStream(target);
  wr.on('error', function(err) {
    cb(err);
  });
  wr.on('close', function(err) {
    cb(err);
  });
  rd.pipe(wr);
};

// intercepts stdout and stderr
// returns object with methods:
//   output() : returns captured string
//   release() : must be called when done, returns captured string
module.exports.captureOutput = function captureOutput() {
  var old_stdout_write = process.stdout.write;
  var old_console_error = console.error;

  var captured = '';
  var callback = function(string) {
    captured += string;
  };

  process.stdout.write = (function(write) {
    return function(string, encoding, fd) {
      var args = _.toArray(arguments);
      write.apply(process.stdout, args);

      // only intercept the string
      callback.call(callback, string);
    };
  }(process.stdout.write));

  console.error = (function(log) {
    return function() {
      var args = _.toArray(arguments);
      args.unshift('[ERROR]');
      console.log.apply(console.log, args);

      // string here encapsulates all the args
      callback.call(callback, util.format(args));
    };
  }(console.error));

  return {
    output: function output(err, reply) {
      return captured;
    },
    release: function done(err, reply) {
      process.stdout.write = old_stdout_write;
      console.error = old_console_error;
      return captured;
    }
  }
};