diff --git a/_infrastructure/tests/runner.js b/_infrastructure/tests/runner.js
index 21e6e2ac13..190285474a 100644
--- a/_infrastructure/tests/runner.js
+++ b/_infrastructure/tests/runner.js
@@ -1,4 +1,18 @@
-var ExecResult = (function () {
+//
+// Copyright (c) Microsoft Corporation.  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.
+//
+var ExecResult = (function () {
     function ExecResult() {
         this.stdout = "";
         this.stderr = "";
@@ -63,8 +77,23 @@ var Exec = (function () {
         return new NodeExec();
     }
 })();
+//
+// Copyright (c) Microsoft Corporation.  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.
+//
 var IOUtils;
 (function (IOUtils) {
+    // Creates the directory including its parent if not already present
     function createDirectoryStructure(ioHost, dirName) {
         if (ioHost.directoryExists(dirName)) {
             return;
@@ -77,6 +106,7 @@ var IOUtils;
         ioHost.createDirectory(dirName);
     }
 
+    // Creates a file including its directory structure if not already present
     function createFileAndFolderStructure(ioHost, fileName, useUTF8) {
         var path = ioHost.resolvePath(fileName);
         var dirName = ioHost.dirName(path);
@@ -96,6 +126,8 @@ var IOUtils;
 })(IOUtils || (IOUtils = {}));
 
 var IO = (function () {
+    // Create an IO object for use inside WindowsScriptHost hosts
+    // Depends on WSCript and FileSystemObject
     function getWindowsScriptHostIO() {
         var fso = new ActiveXObject("Scripting.FileSystemObject");
         var streamObjectPool = [];
@@ -133,6 +165,7 @@ var IO = (function () {
                         streamObj.Charset = 'utf-8';
                     }
 
+                    // Read the whole file
                     var str = streamObj.ReadText(-1);
                     streamObj.Close();
                     releaseStreamObject(streamObj);
@@ -164,6 +197,7 @@ var IO = (function () {
                             var content = this.readFile(path);
                             return { content: content, path: path };
                         } catch (err) {
+                            //Tools.CompilerDiagnostics.debugPrint("Could not find " + path + ", trying parent");
                         }
                     } else {
                         rootPath = fso.GetParentFolderName(fso.GetAbsolutePathName(rootPath));
@@ -287,6 +321,8 @@ var IO = (function () {
     }
     ;
 
+    // Create an IO object for use inside Node.js hosts
+    // Depends on 'fs' and 'path' modules
     function getNodeIO() {
         var _fs = require('fs');
         var _path = require('path');
@@ -299,6 +335,8 @@ var IO = (function () {
                     switch (buffer[0]) {
                         case 0xFE:
                             if (buffer[1] == 0xFF) {
+                                // utf16-be. Reading the buffer as big endian is not supported, so convert it to
+                                // Little Endian first
                                 var i = 0;
                                 while ((i + 1) < buffer.length) {
                                     var temp = buffer[i];
@@ -311,15 +349,18 @@ var IO = (function () {
                             break;
                         case 0xFF:
                             if (buffer[1] == 0xFE) {
+                                // utf16-le
                                 return buffer.toString("ucs2", 2);
                             }
                             break;
                         case 0xEF:
                             if (buffer[1] == 0xBB) {
+                                // utf-8
                                 return buffer.toString("utf8", 3);
                             }
                     }
 
+                    // Default behaviour
                     return buffer.toString();
                 } catch (e) {
                     IOUtils.throwIOError("Error reading file \"" + file + "\".", e);
@@ -419,6 +460,7 @@ var IO = (function () {
                             var content = this.readFile(path);
                             return { content: content, path: path };
                         } catch (err) {
+                            //Tools.CompilerDiagnostics.debugPrint(("Could not find " + path) + ", trying parent");
                         }
                     } else {
                         var parentPath = _path.resolve(rootPath, "..");
@@ -504,10 +546,14 @@ var IO = (function () {
     ;
 
     if (typeof ActiveXObject === "function")
-        return getWindowsScriptHostIO(); else if (typeof require === "function")
-        return getNodeIO(); else
+        return getWindowsScriptHostIO();
+else if (typeof require === "function")
+        return getNodeIO();
+else
         return null;
 })();
+/// <reference path='src/exec.ts' />
+/// <reference path='src/io.ts' />
 var DefinitelyTyped;
 (function (DefinitelyTyped) {
     (function (TestManager) {
@@ -537,7 +583,7 @@ var DefinitelyTyped;
             function Tsc() {
             }
             Tsc.run = function (tsfile, callback) {
-                Exec.exec('node ./_infrastructure/tests/typescript/tsc.js ', [tsfile], function (ExecResult) {
+                Exec.exec('node ./_infrastructure/tests/typescript/tsc.js --module commonjs ', [tsfile], function (ExecResult) {
                     callback(ExecResult);
                 });
             };
diff --git a/_infrastructure/tests/runner.ts b/_infrastructure/tests/runner.ts
index 0d42252867..3c8f162108 100644
--- a/_infrastructure/tests/runner.ts
+++ b/_infrastructure/tests/runner.ts
@@ -28,7 +28,7 @@ module DefinitelyTyped {
 
 		class Tsc {
 			public static run(tsfile: string, callback: Function) {
-				Exec.exec('node ./_infrastructure/tests/typescript/tsc.js ', [tsfile], (ExecResult) => {
+				Exec.exec('node ./_infrastructure/tests/typescript/tsc.js --module commonjs ', [tsfile], (ExecResult) => {
 				    callback(ExecResult);
 				});
 			}
diff --git a/_infrastructure/tests/src/io.js b/_infrastructure/tests/src/io.js
index 0058d59f93..0f8b9516c8 100644
--- a/_infrastructure/tests/src/io.js
+++ b/_infrastructure/tests/src/io.js
@@ -1,5 +1,20 @@
-var IOUtils;
+//
+// Copyright (c) Microsoft Corporation.  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.
+//
+var IOUtils;
 (function (IOUtils) {
+    // Creates the directory including its parent if not already present
     function createDirectoryStructure(ioHost, dirName) {
         if (ioHost.directoryExists(dirName)) {
             return;
@@ -12,6 +27,7 @@
         ioHost.createDirectory(dirName);
     }
 
+    // Creates a file including its directory structure if not already present
     function createFileAndFolderStructure(ioHost, fileName, useUTF8) {
         var path = ioHost.resolvePath(fileName);
         var dirName = ioHost.dirName(path);
@@ -31,6 +47,8 @@
 })(IOUtils || (IOUtils = {}));
 
 var IO = (function () {
+    // Create an IO object for use inside WindowsScriptHost hosts
+    // Depends on WSCript and FileSystemObject
     function getWindowsScriptHostIO() {
         var fso = new ActiveXObject("Scripting.FileSystemObject");
         var streamObjectPool = [];
@@ -68,6 +86,7 @@ var IO = (function () {
                         streamObj.Charset = 'utf-8';
                     }
 
+                    // Read the whole file
                     var str = streamObj.ReadText(-1);
                     streamObj.Close();
                     releaseStreamObject(streamObj);
@@ -99,6 +118,7 @@ var IO = (function () {
                             var content = this.readFile(path);
                             return { content: content, path: path };
                         } catch (err) {
+                            //Tools.CompilerDiagnostics.debugPrint("Could not find " + path + ", trying parent");
                         }
                     } else {
                         rootPath = fso.GetParentFolderName(fso.GetAbsolutePathName(rootPath));
@@ -222,6 +242,8 @@ var IO = (function () {
     }
     ;
 
+    // Create an IO object for use inside Node.js hosts
+    // Depends on 'fs' and 'path' modules
     function getNodeIO() {
         var _fs = require('fs');
         var _path = require('path');
@@ -234,6 +256,8 @@ var IO = (function () {
                     switch (buffer[0]) {
                         case 0xFE:
                             if (buffer[1] == 0xFF) {
+                                // utf16-be. Reading the buffer as big endian is not supported, so convert it to
+                                // Little Endian first
                                 var i = 0;
                                 while ((i + 1) < buffer.length) {
                                     var temp = buffer[i];
@@ -246,15 +270,18 @@ var IO = (function () {
                             break;
                         case 0xFF:
                             if (buffer[1] == 0xFE) {
+                                // utf16-le
                                 return buffer.toString("ucs2", 2);
                             }
                             break;
                         case 0xEF:
                             if (buffer[1] == 0xBB) {
+                                // utf-8
                                 return buffer.toString("utf8", 3);
                             }
                     }
 
+                    // Default behaviour
                     return buffer.toString();
                 } catch (e) {
                     IOUtils.throwIOError("Error reading file \"" + file + "\".", e);
@@ -354,6 +381,7 @@ var IO = (function () {
                             var content = this.readFile(path);
                             return { content: content, path: path };
                         } catch (err) {
+                            //Tools.CompilerDiagnostics.debugPrint(("Could not find " + path) + ", trying parent");
                         }
                     } else {
                         var parentPath = _path.resolve(rootPath, "..");
@@ -439,7 +467,9 @@ var IO = (function () {
     ;
 
     if (typeof ActiveXObject === "function")
-        return getWindowsScriptHostIO(); else if (typeof require === "function")
-        return getNodeIO(); else
+        return getWindowsScriptHostIO();
+else if (typeof require === "function")
+        return getNodeIO();
+else
         return null;
 })();
diff --git a/_infrastructure/tests/src/io.ts b/_infrastructure/tests/src/io.ts
index 9a3bdf8ad5..6fce754893 100644
--- a/_infrastructure/tests/src/io.ts
+++ b/_infrastructure/tests/src/io.ts
@@ -25,11 +25,11 @@ interface IFileWatcher {
 interface IIO {
     readFile(path: string): string;
     writeFile(path: string, contents: string): void;
-    createFile(path: string, useUTF8?: bool): ITextWriter;
+    createFile(path: string, useUTF8?: boolean): ITextWriter;
     deleteFile(path: string): void;
-    dir(path: string, re?: RegExp, options?: { recursive?: bool; deep?: number; }): string[];
-    fileExists(path: string): bool;
-    directoryExists(path: string): bool;
+    dir(path: string, re?: RegExp, options?: { recursive?: boolean; deep?: number; }): string[];
+    fileExists(path: string): boolean;
+    directoryExists(path: string): boolean;
     createDirectory(path: string): void;
     resolvePath(path: string): string;
     dirName(path: string): string;
@@ -60,7 +60,7 @@ module IOUtils {
     }
 
     // Creates a file including its directory structure if not already present
-    export function createFileAndFolderStructure(ioHost: IIO, fileName: string, useUTF8?: bool) {
+    export function createFileAndFolderStructure(ioHost: IIO, fileName: string, useUTF8?: boolean) {
         var path = ioHost.resolvePath(fileName);
         var dirName = ioHost.dirName(path);
         createDirectoryStructure(ioHost, dirName);
@@ -78,7 +78,7 @@ module IOUtils {
 
 // Declare dependencies needed for all supported hosts
 declare class Enumerator {
-    public atEnd(): bool;
+    public atEnd(): boolean;
     public moveNext();
     public item(): any;
     constructor (o: any);
@@ -160,7 +160,7 @@ var IO = (function() {
                 file.Close();
             },
 
-            fileExists: function(path: string): bool {
+            fileExists: function(path: string): boolean {
                 return fso.FileExists(path);
             },
 
@@ -250,7 +250,7 @@ var IO = (function() {
             },
 
             dir: function(path, spec?, options?) {
-                options = options || <{ recursive?: bool; deep?: number; }>{};
+                options = options || <{ recursive?: boolean; deep?: number; }>{};
                 function filesInFolder(folder, root): string[]{
                     var paths = [];
                     var fc: Enumerator;
@@ -365,7 +365,7 @@ var IO = (function() {
                     IOUtils.throwIOError("Couldn't delete file '" + path + "'.", e);
                 }
             },
-            fileExists: function(path): bool {
+            fileExists: function(path): boolean {
                 return _fs.existsSync(path);
             },
             createFile: function(path, useUTF8?) {
@@ -395,7 +395,7 @@ var IO = (function() {
                 };
             },
             dir: function dir(path, spec?, options?) {
-                options = options || <{ recursive?: bool; deep?: number; }>{};
+                options = options || <{ recursive?: boolean; deep?: number; }>{};
 
                 function filesInFolder(folder: string, deep?: number): string[]{
                     var paths = [];
@@ -427,7 +427,7 @@ var IO = (function() {
                 }
             },
 
-            directoryExists: function(path: string): bool {
+            directoryExists: function(path: string): boolean {
                 return _fs.existsSync(path) && _fs.lstatSync(path).isDirectory();
             },
             resolvePath: function(path: string): string {