executor: pass correct `this` to middleware

Fix the bug "can't configure passport#initialize in middleware.json"

lib/executor.js

@@ -280,7 +280,7 @@ function setupMiddleware(app, instructions) {
         data.fragment ? ('#' + data.fragment) : '');
     var factory = require(data.sourceFile);
     if (data.fragment) {
-      factory = factory[data.fragment];
+      factory = factory[data.fragment].bind(factory);
     }
     assert(typeof factory === 'function',
       'Middleware factory must be a function');

test/executor.test.js

@@ -467,6 +467,29 @@ describe('executor', function() {
 
     expect(app.componentOptions).to.eql({ option: 'value' });
   });
+
+  it('configures middleware (that requires `this`)', function(done) {
+    var passportPath = require.resolve('./fixtures/passport');
+
+    boot.execute(app, someInstructions({
+      middleware: {
+        phases: ['auth'],
+        middleware: [
+          {
+            sourceFile: passportPath,
+            fragment: 'initialize',
+            config: {
+              phase: 'auth:before'
+            }
+          }
+        ]
+      }
+    }));
+
+    supertest(app)
+      .get('/')
+      .expect('passport', 'initialized', done);
+  });
 });
 
 function assertValidDataSource(dataSource) {

test/fixtures/passport.js

@@ -0,0 +1,19 @@
+var framework = {
+  initialize: function(passport) {
+    return function(req, res, next) {
+      req._passport = passport;
+      res.setHeader('passport', 'initialized');
+      next();
+    };
+  }
+};
+
+var Passport = function() {
+  this._framework = framework;
+};
+
+Passport.prototype.initialize = function() {
+  return this._framework.initialize(this);
+};
+
+module.exports = new Passport();