[fixes ember-cli#2338] automatically prevent spotlight from indexing dist and tmp

Thanks to @eccegordo for the pro-tip!

Author: stefanpenner

.jshintrc

@@ -9,6 +9,7 @@
     "after",
     "-Promise"
   ],
+  "expr": true,
   "proto": true,
   "strict": true,
   "indent": 2,

lib/models/builder.js

@@ -9,6 +9,8 @@ var SilentError = require('../errors/silent');
 var chalk       = require('chalk');
 var cpd         = require('ember-cli-copy-dereference');
 
+var attemptNeverIndex = require('../utilities/attempt-never-index');
+
 var signalsTrapped = false;
 
 module.exports = Task.extend({
@@ -71,6 +73,8 @@ module.exports = Task.extend({
         fs.mkdirsSync(outputPath);
       }
 
+      attemptNeverIndex(outputPath);
+
       resolve(cpd.sync(inputPath, outputPath));
     });
   },
@@ -109,6 +113,8 @@ module.exports = Task.extend({
       args.push(arguments[i]);
     }
 
+    attemptNeverIndex('tmp');
+
     return this.processAddonBuildSteps('preBuild')
        .then(function() {
          return self.builder.build.apply(self.builder, args);

lib/utilities/attempt-never-index.js

@@ -0,0 +1,20 @@
+'use strict';
+
+var isDarwin = /darwin/i.test(require('os').type());
+var debug = require('debug')('ember-cli:utilities/attempt-metadata-index-file');
+
+module.exports = function(dir) {
+  var path = dir + '/.metadata_never_index';
+
+  if (!isDarwin) {
+    debug('not darwin, skipping %s (which hints to spotlight to prevent indexing)', path);
+    return;
+  }
+
+  debug('creating: %s (to prevent spotlight indexing)', path);
+
+  var fs = require('fs-extra');
+
+  fs.mkdirsSync(dir);
+  fs.writeFileSync(path);
+};

tests/unit/utilities/attempt-never-index-test.js

@@ -0,0 +1,31 @@
+'use strict';
+
+var attemptNeverIndex= require('../../../lib/utilities/attempt-never-index');
+var quickTemp = require('quick-temp');
+var fs = require('fs-extra');
+var expect = require('chai').expect;
+var isDarwin = /darwin/i.test(require('os').type());
+
+describe('attempt-never-index', function() {
+  var context = {};
+  var tmpPath;
+  before(function() {
+    tmpPath = quickTemp.makeOrRemake(context, 'attempt-never-index');
+  });
+
+  after(function() {
+    quickTemp.remove(context, 'attempt-never-index');
+  });
+
+  it('sets the hint to spotlight if possible', function() {
+    expect(fs.existsSync(tmpPath + '/.metadata_never_index')).to.false;
+
+    attemptNeverIndex(tmpPath);
+
+    if (isDarwin) {
+      expect(fs.existsSync(tmpPath + '/.metadata_never_index')).to.true;
+    } else {
+      expect(fs.existsSync(tmpPath + '/.metadata_never_index')).to.false;
+    }
+  });
+});