From cb54c11d84ce3aba5d851eea74e8db26960bbde9 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 07:39:11 +1100
Subject: [PATCH 01/14] add esnext tests

---
 test/_helper.js                               | 13 ++++-
 .../arguments-refers-to-parent-function.js    | 57 +++++++++++++++++++
 ...es-not-bind-this-from-standard-function.js |  5 ++
 .../empty-arrow-function.js                   |  2 +
 .../handles-nested-context-bindings.js        | 12 ++++
 ...rens-for-low-precedence-expression-body.js |  2 +
 .../object-literal-needs-parens.js            |  2 +
 .../only-lexical-this-not-dynamic-this.js     |  7 +++
 .../passed-to-function.js                     |  2 +
 .../single-param-does-not-need-parens.js      |  2 +
 .../esnext-es6-classes/anonymous-class.js     | 29 ++++++++++
 .../esnext-es6-classes/call-super-function.js | 21 +++++++
 .../esnext-es6-classes/class-expressions.js   |  9 +++
 .../esnext-es6-classes/class-extend.js        | 15 +++++
 .../class-with-constructor.js                 | 14 +++++
 .../class-with-method-declaration.js          | 10 ++++
 .../esnext-es6-classes/empty-named-class.js   |  5 ++
 .../esnext-es6-classes/enumerable.js          | 20 +++++++
 .../explicit-super-in-constructor.js          | 15 +++++
 .../esnext-es6-classes/extends-null.js        |  4 ++
 .../esnext-es6-classes/getter-setter-super.js | 15 +++++
 .../esnext-es6-classes/getter-setter.js       | 28 +++++++++
 .../esnext-es6-classes/implicit-superclass.js |  9 +++
 .../method-declaration-with-arguments.js      |  7 +++
 .../methods-are-writable.js                   | 12 ++++
 .../methods-with-rest-params.js               | 28 +++++++++
 .../esnext-es6-classes/static-getter.js       | 12 ++++
 .../esnext-es6-classes/static-method.js       | 30 ++++++++++
 .../esnext-es6-classes/static-setter.js       |  7 +++
 .../esnext-es6-classes/strict-mode.js         | 23 ++++++++
 .../esnext-es6-classes/super-change-proto.js  | 20 +++++++
 .../accessor.js                               |  8 +++
 .../esnext-es6-computed-properties/method.js  |  3 +
 .../esnext-es6-computed-properties/nested.js  |  4 ++
 .../esnext-es6-computed-properties/simple.js  |  3 +
 .../esnext-es6-default-parameters/arity.js    |  3 +
 .../arrow-function.js                         |  8 +++
 .../null-vs-undefined.js                      |  5 ++
 .../esnext-es6-default-parameters/scope.js    | 11 ++++
 .../simple-function.js                        |  4 ++
 .../method-arguments.js                       |  7 +++
 .../method-context.js                         |  9 +++
 .../method-has-name.js                        |  7 +++
 .../method-is-not-in-scope-inside.js          |  9 +++
 .../method-to-string.js                       | 10 ++++
 .../esnext-es6-object-concise/method.js       |  7 +++
 .../esnext-es6-rest-parameters/arrow-fn.js    |  8 +++
 .../esnext-es6-rest-parameters/declaration.js |  8 +++
 .../esnext-es6-rest-parameters/rest.js        |  8 +++
 .../esnext-es6-spread/arguments-as-array.js   |  6 ++
 .../esnext-es6-spread/array-literal.js        |  3 +
 .../call-with-array-literal.js                |  5 ++
 .../inside-function-expression.js             | 10 ++++
 .../esnext-es6-spread/iterator.js             | 19 +++++++
 .../esnext-es6-spread/new-object.js           | 11 ++++
 .../esnext-es6-spread/preserve-context.js     | 35 ++++++++++++
 .../esnext-es6-spread/simple-function-call.js |  6 ++
 .../esnext-es6-templates/multi-line.js        |  4 ++
 .../nested-interpolation.js                   |  4 ++
 .../esnext-es6-templates/no-interpolation.js  |  2 +
 .../raw-tagged-template-expression.js         |  6 ++
 .../simple-interpolation.js                   |  2 +
 .../tagged-template-expression.js             | 26 +++++++++
 63 files changed, 695 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/arguments-refers-to-parent-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/empty-arrow-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/handles-nested-context-bindings.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/no-parens-for-low-precedence-expression-body.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/object-literal-needs-parens.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/only-lexical-this-not-dynamic-this.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/passed-to-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-arrow-functions/single-param-does-not-need-parens.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/anonymous-class.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/call-super-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/class-expressions.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/class-extend.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/class-with-constructor.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/class-with-method-declaration.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/empty-named-class.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/enumerable.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/explicit-super-in-constructor.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/extends-null.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/getter-setter-super.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/getter-setter.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/implicit-superclass.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/method-declaration-with-arguments.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/methods-are-writable.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/methods-with-rest-params.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/static-getter.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/static-method.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/static-setter.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/strict-mode.js
 create mode 100644 test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
 create mode 100644 test/fixtures/transformation/esnext-es6-computed-properties/accessor.js
 create mode 100644 test/fixtures/transformation/esnext-es6-computed-properties/method.js
 create mode 100644 test/fixtures/transformation/esnext-es6-computed-properties/nested.js
 create mode 100644 test/fixtures/transformation/esnext-es6-computed-properties/simple.js
 create mode 100644 test/fixtures/transformation/esnext-es6-default-parameters/arity.js
 create mode 100644 test/fixtures/transformation/esnext-es6-default-parameters/arrow-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-default-parameters/null-vs-undefined.js
 create mode 100644 test/fixtures/transformation/esnext-es6-default-parameters/scope.js
 create mode 100644 test/fixtures/transformation/esnext-es6-default-parameters/simple-function.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method-arguments.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method-context.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method-has-name.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method-is-not-in-scope-inside.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method-to-string.js
 create mode 100644 test/fixtures/transformation/esnext-es6-object-concise/method.js
 create mode 100644 test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
 create mode 100644 test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
 create mode 100644 test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/arguments-as-array.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/array-literal.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/call-with-array-literal.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/inside-function-expression.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/iterator.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/new-object.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/preserve-context.js
 create mode 100644 test/fixtures/transformation/esnext-es6-spread/simple-function-call.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/multi-line.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/nested-interpolation.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/no-interpolation.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/raw-tagged-template-expression.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/simple-interpolation.js
 create mode 100644 test/fixtures/transformation/esnext-es6-templates/tagged-template-expression.js

diff --git a/test/_helper.js b/test/_helper.js
index a988f30d73..8273a11443 100644
--- a/test/_helper.js
+++ b/test/_helper.js
@@ -1,5 +1,6 @@
-var fs = require("fs");
-var _  = require("lodash");
+var path = require("path");
+var fs   = require("fs");
+var _    = require("lodash");
 
 var humanise = function (val) {
   return val.replace(/-/g, " ");
@@ -37,7 +38,6 @@ exports.get = function (entryName) {
 
     _.each(fs.readdirSync(suite.filename), function (taskName) {
       var taskDir = suite.filename + "/" + taskName;
-      if (fs.statSync(taskDir).isFile()) return;
 
       var actualLocAlias = suiteName + "/" + taskName + "/actual.js";
       var expectLocAlias = suiteName + "/" + taskName + "/expected.js";
@@ -47,6 +47,13 @@ exports.get = function (entryName) {
       var expectLoc = taskDir + "/expected.js";
       var execLoc   = taskDir + "/exec.js";
 
+      if (fs.statSync(taskDir).isFile()) {
+        var ext = path.extname(taskDir);
+        if (ext === ".json") return;
+
+        execLoc = taskDir;
+      }
+
       var taskOpts = _.merge({
         filenameRelative: expectLocAlias,
         sourceFileName:   actualLocAlias,
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/arguments-refers-to-parent-function.js b/test/fixtures/transformation/esnext-es6-arrow-functions/arguments-refers-to-parent-function.js
new file mode 100644
index 0000000000..d299fb5379
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/arguments-refers-to-parent-function.js
@@ -0,0 +1,57 @@
+function makeMultiplier() {
+  // `arguments` should refer to `makeMultiplier`'s arguments.
+  return (n) => [].slice.call(arguments).reduce((a, b) => a * b) * n;
+}
+
+function toArray() {
+  // Intentionally nest arrow functions to ensure `arguments` is put inside
+  // `toArray`'s scope.
+  return (() => (arguments, (() => [].slice.call(arguments)).call())).call();
+}
+
+function returnDotArguments(object) {
+  // Ensure `arguments` is not treated as a reference to the magic value.
+  return (() => object.arguments).call();
+}
+
+function returnArgumentsObject() {
+  // Ensure `arguments` is not treated as a reference to the magic value.
+  return (() => ({arguments: 1})).call();
+}
+
+function makeArgumentsReturner() {
+  return (() => function() {
+    return [].slice.call(arguments);
+  }).call();
+}
+
+// i.e. 2 * 3 * 4 == 24, not 16 (4 * 4)
+assert.equal(
+  makeMultiplier(2, 3)(4),
+  24,
+  'ensure `arguments` is hoisted out to the first non-arrow scope'
+);
+
+assert.deepEqual(
+  toArray(1, 2, 3),
+  [1, 2, 3],
+  'ensure `arguments` is hoisted out to the first non-arrow scope'
+);
+
+assert.equal(
+  returnDotArguments({arguments: 1}),
+  1,
+  'member accesses with `arguments` property should not be replaced'
+);
+
+assert.deepEqual(
+  returnArgumentsObject(),
+  {arguments: 1},
+  'object property keys named `arguments` should not be replaced'
+);
+
+assert.deepEqual(
+  makeArgumentsReturner()(1, 2, 3),
+  [1, 2, 3],
+  'arguments should not be hoisted from inside non-arrow functions'
+);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js b/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
new file mode 100644
index 0000000000..c2eeddcc3e
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
@@ -0,0 +1,5 @@
+var dynamicThisGetter = () => function(){ return this; };
+assert.equal(
+  normalize('('+dynamicThisGetter.toString()+')'),
+  normalize('(function(){ return function(){ return this; }; })')
+);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/empty-arrow-function.js b/test/fixtures/transformation/esnext-es6-arrow-functions/empty-arrow-function.js
new file mode 100644
index 0000000000..0b95435853
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/empty-arrow-function.js
@@ -0,0 +1,2 @@
+var empty = () => {};
+assert.equal(empty(), undefined);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/handles-nested-context-bindings.js b/test/fixtures/transformation/esnext-es6-arrow-functions/handles-nested-context-bindings.js
new file mode 100644
index 0000000000..03041f0297
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/handles-nested-context-bindings.js
@@ -0,0 +1,12 @@
+var obj = {
+  method: function() {
+    return () => (this, () => this);
+  },
+
+  method2: function() {
+    return () => () => this;
+  }
+};
+
+assert.strictEqual(obj.method()()(), obj);
+assert.strictEqual(obj.method2()()(), obj);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/no-parens-for-low-precedence-expression-body.js b/test/fixtures/transformation/esnext-es6-arrow-functions/no-parens-for-low-precedence-expression-body.js
new file mode 100644
index 0000000000..66fad996e5
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/no-parens-for-low-precedence-expression-body.js
@@ -0,0 +1,2 @@
+var square = x => x * x;
+assert.equal(square(4), 16);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/object-literal-needs-parens.js b/test/fixtures/transformation/esnext-es6-arrow-functions/object-literal-needs-parens.js
new file mode 100644
index 0000000000..3ec553b180
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/object-literal-needs-parens.js
@@ -0,0 +1,2 @@
+var keyMaker = val => ({ key: val });
+assert.deepEqual(keyMaker(9), { key: 9 });
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/only-lexical-this-not-dynamic-this.js b/test/fixtures/transformation/esnext-es6-arrow-functions/only-lexical-this-not-dynamic-this.js
new file mode 100644
index 0000000000..68f68c14dc
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/only-lexical-this-not-dynamic-this.js
@@ -0,0 +1,7 @@
+var obj = {
+  method: function() {
+    return () => this;
+  }
+};
+
+assert.strictEqual(obj.method()(), obj);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/passed-to-function.js b/test/fixtures/transformation/esnext-es6-arrow-functions/passed-to-function.js
new file mode 100644
index 0000000000..75fbefbacd
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/passed-to-function.js
@@ -0,0 +1,2 @@
+var odds = [0, 2, 4].map(v => v + 1);
+assert.deepEqual(odds, [1, 3, 5]);
diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/single-param-does-not-need-parens.js b/test/fixtures/transformation/esnext-es6-arrow-functions/single-param-does-not-need-parens.js
new file mode 100644
index 0000000000..c2b56e7bbc
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/single-param-does-not-need-parens.js
@@ -0,0 +1,2 @@
+var identity = x => x;
+assert.equal(identity(1), 1);
diff --git a/test/fixtures/transformation/esnext-es6-classes/anonymous-class.js b/test/fixtures/transformation/esnext-es6-classes/anonymous-class.js
new file mode 100644
index 0000000000..231ba49b9e
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/anonymous-class.js
@@ -0,0 +1,29 @@
+var Animal = class {
+  sayHi() {
+    return 'Hi, I am a '+this.type()+'.';
+  }
+
+  static getName() {
+    return 'Animal';
+  }
+};
+
+var Dog = class extends Animal {
+  type() { return 'dog'; }
+
+  sayHi() {
+    return super() + ' WOOF!';
+  }
+
+  static getName() {
+    return super() + '/Dog';
+  }
+};
+
+assert.equal(new Dog().sayHi(), 'Hi, I am a dog. WOOF!');
+assert.equal(Dog.getName(), 'Animal/Dog');
+
+var count = 0;
+var Cat = class extends (function(){ count++; return Animal; })() {};
+
+assert.equal(count, 1);
diff --git a/test/fixtures/transformation/esnext-es6-classes/call-super-function.js b/test/fixtures/transformation/esnext-es6-classes/call-super-function.js
new file mode 100644
index 0000000000..5c7efe0dc6
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/call-super-function.js
@@ -0,0 +1,21 @@
+class Animal {
+  sayHi() {
+    return 'I am an animal.'
+  }
+
+  sayOther() {
+    return 'WAT?!';
+  }
+}
+
+class Horse extends Animal {
+  sayHi() {
+    return super.sayOther();
+  }
+
+  sayOther() {
+    return 'I see dead objects.';
+  }
+}
+
+assert.equal(new Horse().sayHi(), 'WAT?!');
diff --git a/test/fixtures/transformation/esnext-es6-classes/class-expressions.js b/test/fixtures/transformation/esnext-es6-classes/class-expressions.js
new file mode 100644
index 0000000000..1c2bb96a80
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/class-expressions.js
@@ -0,0 +1,9 @@
+var Person = (class Person {});
+assert.equal(typeof Person, 'function');
+
+assert.equal(
+  (function(){ return (class Person {}); })().name,
+  'Person'
+);
+
+assert.equal(typeof (class {}), 'function');
diff --git a/test/fixtures/transformation/esnext-es6-classes/class-extend.js b/test/fixtures/transformation/esnext-es6-classes/class-extend.js
new file mode 100644
index 0000000000..56035dd0b6
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/class-extend.js
@@ -0,0 +1,15 @@
+class Animal {
+  sayHi() {
+    return 'Hi, I am a '+this.type()+'.';
+  }
+}
+
+class Dog extends Animal {
+  type() { return 'dog'; }
+
+  sayHi() {
+    return super() + ' WOOF!';
+  }
+}
+
+assert.equal(new Dog().sayHi(), 'Hi, I am a dog. WOOF!');
diff --git a/test/fixtures/transformation/esnext-es6-classes/class-with-constructor.js b/test/fixtures/transformation/esnext-es6-classes/class-with-constructor.js
new file mode 100644
index 0000000000..4dcf3296f0
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/class-with-constructor.js
@@ -0,0 +1,14 @@
+class Multiplier {
+  constructor(n=1) {
+    this.n = n;
+  }
+
+  multiply(n=1) {
+    return n * this.n;
+  }
+}
+
+assert.equal(new Multiplier().n, 1);
+assert.equal(new Multiplier(6).n, 6);
+assert.equal(new Multiplier().multiply(), 1);
+assert.equal(new Multiplier(2).multiply(3), 6);
diff --git a/test/fixtures/transformation/esnext-es6-classes/class-with-method-declaration.js b/test/fixtures/transformation/esnext-es6-classes/class-with-method-declaration.js
new file mode 100644
index 0000000000..f8d9d7a207
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/class-with-method-declaration.js
@@ -0,0 +1,10 @@
+class Person {
+  getName() {
+    return this.firstName + ' ' + this.lastName;
+  }
+}
+
+var me = new Person();
+me.firstName = 'Brian';
+me.lastName = 'Donovan';
+assert.equal(me.getName(), 'Brian Donovan');
diff --git a/test/fixtures/transformation/esnext-es6-classes/empty-named-class.js b/test/fixtures/transformation/esnext-es6-classes/empty-named-class.js
new file mode 100644
index 0000000000..602a6702d3
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/empty-named-class.js
@@ -0,0 +1,5 @@
+class Foo {
+}
+
+assert.equal(new Foo().constructor, Foo, 'Foo instances should have Foo as constructor');
+assert.ok(new Foo() instanceof Foo, 'Foo instances should be `instanceof` Foo');
diff --git a/test/fixtures/transformation/esnext-es6-classes/enumerable.js b/test/fixtures/transformation/esnext-es6-classes/enumerable.js
new file mode 100644
index 0000000000..fe5c02d113
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/enumerable.js
@@ -0,0 +1,20 @@
+class Point {
+  constructor(x, y) {
+    this.x = x;
+    this.y = y;
+  }
+
+  toString() {
+    return '(' + this.x + ', ' + this.y + ')';
+  }
+}
+
+var point = new Point(1, 2);
+var keys = [];
+
+for (var key in point) {
+  keys.push(key);
+}
+
+assert.equal(point.toString(), '(1, 2)');
+assert.deepEqual(keys.sort(), ['x', 'y']);
diff --git a/test/fixtures/transformation/esnext-es6-classes/explicit-super-in-constructor.js b/test/fixtures/transformation/esnext-es6-classes/explicit-super-in-constructor.js
new file mode 100644
index 0000000000..d30f21cba5
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/explicit-super-in-constructor.js
@@ -0,0 +1,15 @@
+class Point {
+  constructor(x, y) {
+    this.x = x;
+    this.y = y;
+  }
+}
+
+class ZeroPoint extends Point {
+  constructor() {
+    super(0, 0);
+  }
+}
+
+assert.equal(new ZeroPoint().x, 0);
+assert.equal(new ZeroPoint().y, 0);
diff --git a/test/fixtures/transformation/esnext-es6-classes/extends-null.js b/test/fixtures/transformation/esnext-es6-classes/extends-null.js
new file mode 100644
index 0000000000..fa3821d8c7
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/extends-null.js
@@ -0,0 +1,4 @@
+class Obj extends null {}
+
+assert.strictEqual(Obj.toString, Function.toString);
+assert.strictEqual(new Obj().toString, undefined);
diff --git a/test/fixtures/transformation/esnext-es6-classes/getter-setter-super.js b/test/fixtures/transformation/esnext-es6-classes/getter-setter-super.js
new file mode 100644
index 0000000000..98d7bc0eea
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/getter-setter-super.js
@@ -0,0 +1,15 @@
+class Animal {
+  get sound() {
+    return 'I am a ' + this.type + '.';
+  }
+}
+
+class Cat extends Animal {
+  get type() { return 'cat'; }
+
+  get sound() {
+    return super.sound + ' MEOW!';
+  }
+}
+
+assert.equal(new Cat().sound, 'I am a cat. MEOW!');
diff --git a/test/fixtures/transformation/esnext-es6-classes/getter-setter.js b/test/fixtures/transformation/esnext-es6-classes/getter-setter.js
new file mode 100644
index 0000000000..8f9519f9ba
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/getter-setter.js
@@ -0,0 +1,28 @@
+class Person {
+  constructor(firstName, lastName) {
+    this.firstName = firstName;
+    this.lastName = lastName;
+  }
+
+  get name() {
+    return this.firstName + ' ' + this.lastName;
+  }
+
+  set name(name) {
+    var parts = name.split(' ');
+    this.firstName = parts[0];
+    this.lastName = parts[1];
+  }
+}
+
+var mazer = new Person('Mazer', 'Rackham');
+assert.equal(mazer.name, 'Mazer Rackham');
+mazer.name = 'Ender Wiggin';
+assert.equal(mazer.firstName, 'Ender');
+assert.equal(mazer.lastName, 'Wiggin');
+
+var forLoopProperties = [];
+for (var key in mazer) {
+  forLoopProperties.push(key);
+}
+assert.ok(forLoopProperties.indexOf('name') >= 0, 'getters/setters are enumerable');
diff --git a/test/fixtures/transformation/esnext-es6-classes/implicit-superclass.js b/test/fixtures/transformation/esnext-es6-classes/implicit-superclass.js
new file mode 100644
index 0000000000..96755df101
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/implicit-superclass.js
@@ -0,0 +1,9 @@
+class Obj {
+  constructor() {
+    super();
+  }
+}
+
+assert.doesNotThrow(function() {
+  new Obj();
+});
diff --git a/test/fixtures/transformation/esnext-es6-classes/method-declaration-with-arguments.js b/test/fixtures/transformation/esnext-es6-classes/method-declaration-with-arguments.js
new file mode 100644
index 0000000000..b70c56e68c
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/method-declaration-with-arguments.js
@@ -0,0 +1,7 @@
+class Tripler {
+  triple(n) {
+    return n * 3;
+  }
+}
+
+assert.equal(new Tripler().triple(2), 6);
diff --git a/test/fixtures/transformation/esnext-es6-classes/methods-are-writable.js b/test/fixtures/transformation/esnext-es6-classes/methods-are-writable.js
new file mode 100644
index 0000000000..19ffd5aa73
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/methods-are-writable.js
@@ -0,0 +1,12 @@
+var value;
+
+class Foo {
+  foo() {
+    value = 1;
+  }
+}
+
+var foo = new Foo();
+foo.foo = function() { value = 2; };
+foo.foo();
+assert.equal(value, 2);
diff --git a/test/fixtures/transformation/esnext-es6-classes/methods-with-rest-params.js b/test/fixtures/transformation/esnext-es6-classes/methods-with-rest-params.js
new file mode 100644
index 0000000000..77b7bb0774
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/methods-with-rest-params.js
@@ -0,0 +1,28 @@
+class Joiner {
+  constructor(string) {
+    this.string = string;
+  }
+
+  join(...items) {
+    return items.join(this.string);
+  }
+
+  static join(string, ...items) {
+    var joiner = new this(string);
+    // TODO: use spread params here
+    return joiner.join.apply(joiner, items);
+  }
+}
+
+class ArrayLike {
+  constructor(...items) {
+    items.forEach(function(item, i) {
+      this[i] = item;
+    }.bind(this));
+    this.length = items.length;
+  }
+}
+
+var joiner = new Joiner(' & ');
+assert.equal(joiner.join(4, 5, 6), '4 & 5 & 6');
+assert.equal(new ArrayLike('a', 'b')[1], 'b');
diff --git a/test/fixtures/transformation/esnext-es6-classes/static-getter.js b/test/fixtures/transformation/esnext-es6-classes/static-getter.js
new file mode 100644
index 0000000000..af9fe0afe6
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/static-getter.js
@@ -0,0 +1,12 @@
+class Point {
+  constructor(x, y) {
+    this.x = x;
+    this.y = y;
+  }
+
+  static get ORIGIN() {
+    return new this(0, 0);
+  }
+}
+
+assert.deepEqual(Point.ORIGIN, new Point(0, 0));
\ No newline at end of file
diff --git a/test/fixtures/transformation/esnext-es6-classes/static-method.js b/test/fixtures/transformation/esnext-es6-classes/static-method.js
new file mode 100644
index 0000000000..564fb13c5b
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/static-method.js
@@ -0,0 +1,30 @@
+class Tripler {
+  static triple(n=1) {
+    return n * 3;
+  }
+
+  static toString() {
+    return '3' + super() + '3';
+  }
+}
+
+class MegaTripler extends Tripler {
+  static triple(n=1) {
+    return super(n) * super(n);
+  }
+}
+
+var tripler = new Tripler();
+
+assert.equal(Tripler.triple(), 3);
+assert.equal(Tripler.triple(2), 6);
+assert.equal(tripler.triple, undefined);
+
+assert.equal(Tripler.toString(), '3' + Object.toString.call(Tripler) + '3');
+
+var mega = new MegaTripler();
+
+assert.equal(MegaTripler.triple(2), 36);
+assert.equal(mega.triple, undefined);
+
+assert.equal(MegaTripler.toString(), '3' + Object.toString.call(MegaTripler) + '3');
diff --git a/test/fixtures/transformation/esnext-es6-classes/static-setter.js b/test/fixtures/transformation/esnext-es6-classes/static-setter.js
new file mode 100644
index 0000000000..08fae30af5
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/static-setter.js
@@ -0,0 +1,7 @@
+class Person {
+  static set DB(value) {
+    assert.equal(value, 'mysql');
+  }
+}
+
+Person.DB = 'mysql';
diff --git a/test/fixtures/transformation/esnext-es6-classes/strict-mode.js b/test/fixtures/transformation/esnext-es6-classes/strict-mode.js
new file mode 100644
index 0000000000..d3ece2608e
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/strict-mode.js
@@ -0,0 +1,23 @@
+class StrictModeTest {
+  test() {
+    var implicitThisInsideClassBody = (function() {
+      return this;
+    })();
+    assert.strictEqual(
+      implicitThisInsideClassBody,
+      undefined,
+      'implicit `this` inside class body is undefined'
+    );
+  }
+}
+
+new StrictModeTest().test();
+
+var implicitThisOutsideClass = (function() {
+  return this;
+})();
+assert.notStrictEqual(
+  implicitThisOutsideClass,
+  undefined,
+  'implicit `this` outside class body is not undefined'
+);
diff --git a/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js b/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
new file mode 100644
index 0000000000..d0012cfc0b
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
@@ -0,0 +1,20 @@
+var log = '';
+
+class Base {
+  p() { log += '[Base]'; }
+}
+
+class OtherBase {
+  p() { log += '[OtherBase]'; }
+}
+class Derived extends Base {
+  p() {
+    log += '[Derived]';
+    super();
+    Derived.prototype.__proto__ = OtherBase.prototype;
+    super();
+  }
+}
+
+new Derived().p();
+assert.equal(log, '[Derived][Base][OtherBase]');
diff --git a/test/fixtures/transformation/esnext-es6-computed-properties/accessor.js b/test/fixtures/transformation/esnext-es6-computed-properties/accessor.js
new file mode 100644
index 0000000000..bedcb7785a
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-computed-properties/accessor.js
@@ -0,0 +1,8 @@
+var x = 'y';
+
+var foo = {
+  get [x]() { return this._y; },
+  set [x](v) { this._y = v; }
+};
+
+assert.equal((foo.y = 10, foo.y), 10);
diff --git a/test/fixtures/transformation/esnext-es6-computed-properties/method.js b/test/fixtures/transformation/esnext-es6-computed-properties/method.js
new file mode 100644
index 0000000000..e28e4d18d5
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-computed-properties/method.js
@@ -0,0 +1,3 @@
+var x = 'y';
+assert.equal({[x]: function() { return 10; }}.y(), 10);
+assert.equal({[x + 'y']() { return 10; }}.yy(), 10);
diff --git a/test/fixtures/transformation/esnext-es6-computed-properties/nested.js b/test/fixtures/transformation/esnext-es6-computed-properties/nested.js
new file mode 100644
index 0000000000..ea11b2c6f6
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-computed-properties/nested.js
@@ -0,0 +1,4 @@
+var x = 'y';
+var foo = {[x]: 10, z: {[x]: 10}};
+assert.equal(foo.y + foo.z.y, 20);
+assert.equal({[x]: {[x]: {[x]: 10}}}.y.y.y, 10);
diff --git a/test/fixtures/transformation/esnext-es6-computed-properties/simple.js b/test/fixtures/transformation/esnext-es6-computed-properties/simple.js
new file mode 100644
index 0000000000..21e56afe58
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-computed-properties/simple.js
@@ -0,0 +1,3 @@
+var x = 'y';
+assert.equal({[x]: 10}.y, 10);
+assert.equal({[x + 'y']: 10}.yy, 10);
diff --git a/test/fixtures/transformation/esnext-es6-default-parameters/arity.js b/test/fixtures/transformation/esnext-es6-default-parameters/arity.js
new file mode 100644
index 0000000000..030f3e08ea
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-default-parameters/arity.js
@@ -0,0 +1,3 @@
+assert.equal((function(a){}).length, 1);
+assert.equal((function(a=5){}).length, 0);
+assert.equal((function(a, b, c=5){}).length, 2);
diff --git a/test/fixtures/transformation/esnext-es6-default-parameters/arrow-function.js b/test/fixtures/transformation/esnext-es6-default-parameters/arrow-function.js
new file mode 100644
index 0000000000..66c0068d94
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-default-parameters/arrow-function.js
@@ -0,0 +1,8 @@
+function makeMultiplier(x=1) {
+  return (y=1) => x * y;
+}
+
+assert.equal(makeMultiplier()(), 1);
+assert.equal(makeMultiplier(2)(3), 6);
+assert.deepEqual([1, 2, 3].map(makeMultiplier(2)), [2, 4, 6]);
+assert.deepEqual([undefined, null, 0].map(makeMultiplier(2)), [2, 0, 0]);
diff --git a/test/fixtures/transformation/esnext-es6-default-parameters/null-vs-undefined.js b/test/fixtures/transformation/esnext-es6-default-parameters/null-vs-undefined.js
new file mode 100644
index 0000000000..b028ba3e09
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-default-parameters/null-vs-undefined.js
@@ -0,0 +1,5 @@
+function foo(x=5, y=6) {
+  return [x, y];
+}
+
+assert.deepEqual(foo(undefined, null), [5, null]);
diff --git a/test/fixtures/transformation/esnext-es6-default-parameters/scope.js b/test/fixtures/transformation/esnext-es6-default-parameters/scope.js
new file mode 100644
index 0000000000..54848cd8f2
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-default-parameters/scope.js
@@ -0,0 +1,11 @@
+function call(fn, context=this) {
+  return fn.call(context);
+}
+
+var context = {a: 99};
+
+// use the default parameter
+assert.strictEqual(call.call(context, function(){ return this.a; }), 99);
+
+// explicitly provide the default parameter value
+assert.strictEqual(call(function(){ return this.a; }, context), 99);
diff --git a/test/fixtures/transformation/esnext-es6-default-parameters/simple-function.js b/test/fixtures/transformation/esnext-es6-default-parameters/simple-function.js
new file mode 100644
index 0000000000..d7bf1bfa1c
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-default-parameters/simple-function.js
@@ -0,0 +1,4 @@
+function foo(x=5) {
+  return x;
+}
+assert.equal(foo(), 5);
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method-arguments.js b/test/fixtures/transformation/esnext-es6-object-concise/method-arguments.js
new file mode 100644
index 0000000000..392586fc9b
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method-arguments.js
@@ -0,0 +1,7 @@
+var a = {
+  echo(c) {
+    return c;
+  }
+};
+
+assert.strictEqual(a.echo(1), 1);
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method-context.js b/test/fixtures/transformation/esnext-es6-object-concise/method-context.js
new file mode 100644
index 0000000000..53c4bf3bc7
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method-context.js
@@ -0,0 +1,9 @@
+var a = {
+  b() {
+    return this;
+  }
+};
+
+var context = {};
+assert.strictEqual(a.b(), a);
+assert.strictEqual(a.b.call(context), context);
\ No newline at end of file
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method-has-name.js b/test/fixtures/transformation/esnext-es6-object-concise/method-has-name.js
new file mode 100644
index 0000000000..320ec33b54
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method-has-name.js
@@ -0,0 +1,7 @@
+var a = {
+  b() {
+    return 'c';
+  }
+};
+
+assert.equal(a.b.name, 'b');
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method-is-not-in-scope-inside.js b/test/fixtures/transformation/esnext-es6-object-concise/method-is-not-in-scope-inside.js
new file mode 100644
index 0000000000..4f58980df0
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method-is-not-in-scope-inside.js
@@ -0,0 +1,9 @@
+var b = 1;
+
+var a = {
+  b() {
+    return b;
+  }
+};
+
+assert.equal(a.b(), 1);
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method-to-string.js b/test/fixtures/transformation/esnext-es6-object-concise/method-to-string.js
new file mode 100644
index 0000000000..ba3f86cb78
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method-to-string.js
@@ -0,0 +1,10 @@
+var a = {
+  b() {
+    return b;
+  }
+};
+
+assert.ok(
+  /return b/.test(a.b.toString()),
+  'toString contains body'
+);
\ No newline at end of file
diff --git a/test/fixtures/transformation/esnext-es6-object-concise/method.js b/test/fixtures/transformation/esnext-es6-object-concise/method.js
new file mode 100644
index 0000000000..1707a7aebb
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-object-concise/method.js
@@ -0,0 +1,7 @@
+var a = {
+  b() {
+    return 'c';
+  }
+};
+
+assert.equal(a.b(), 'c');
diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js b/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
new file mode 100644
index 0000000000..34c96f5ecb
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
@@ -0,0 +1,8 @@
+/* jshint esnext: true */
+/* global expect */
+
+var join = (joinStr, ...items) => {
+  return items.join(joinStr);
+};
+
+expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js b/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
new file mode 100644
index 0000000000..1cc45ac46f
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
@@ -0,0 +1,8 @@
+/* jshint esnext: true */
+/* global expect */
+
+function join(joinStr, ...items) {
+  return items.join(joinStr);
+}
+
+expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js b/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
new file mode 100644
index 0000000000..9d0e63e85d
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
@@ -0,0 +1,8 @@
+/* jshint esnext: true */
+/* global expect */
+
+var join = function(joinStr, ...items) {
+  return items.join(joinStr);
+};
+
+expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
diff --git a/test/fixtures/transformation/esnext-es6-spread/arguments-as-array.js b/test/fixtures/transformation/esnext-es6-spread/arguments-as-array.js
new file mode 100644
index 0000000000..d0957e35b4
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/arguments-as-array.js
@@ -0,0 +1,6 @@
+function arrayOf() {
+  return [...arguments];
+}
+
+assert.equal(Object.prototype.toString.call(arrayOf()), '[object Array]');
+assert.deepEqual(arrayOf(1, 2, 3), [1, 2, 3]);
diff --git a/test/fixtures/transformation/esnext-es6-spread/array-literal.js b/test/fixtures/transformation/esnext-es6-spread/array-literal.js
new file mode 100644
index 0000000000..3c1bea826f
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/array-literal.js
@@ -0,0 +1,3 @@
+var names = ['Brian', 'Madeline'];
+assert.deepEqual(['Thomas', ...names], ['Thomas', 'Brian', 'Madeline']);
+assert.deepEqual([1, 2, ...[3, 4, 5]], [1, 2, 3, 4, 5]);
diff --git a/test/fixtures/transformation/esnext-es6-spread/call-with-array-literal.js b/test/fixtures/transformation/esnext-es6-spread/call-with-array-literal.js
new file mode 100644
index 0000000000..19cffabc6d
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/call-with-array-literal.js
@@ -0,0 +1,5 @@
+function sum(...numbers) {
+  return numbers.reduce(function(sum, n) { return n + sum; }, 0);
+}
+
+assert.equal(sum(4, 5, ...[10, 20, 30]), 69);
diff --git a/test/fixtures/transformation/esnext-es6-spread/inside-function-expression.js b/test/fixtures/transformation/esnext-es6-spread/inside-function-expression.js
new file mode 100644
index 0000000000..c2c06da399
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/inside-function-expression.js
@@ -0,0 +1,10 @@
+var object = {
+  list: [],
+
+  append: function(...items) {
+    this.list.push(...items);
+  }
+};
+
+object.append(1, 2, ...[3, 4]);
+assert.deepEqual(object.list, [1, 2, 3, 4]);
diff --git a/test/fixtures/transformation/esnext-es6-spread/iterator.js b/test/fixtures/transformation/esnext-es6-spread/iterator.js
new file mode 100644
index 0000000000..438e7564de
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/iterator.js
@@ -0,0 +1,19 @@
+function Symbol() {}
+Symbol.iterator = '@@iterator';
+
+var obj = {
+  '@@iterator': function() {
+    var ttl = 3;
+    return {
+      next: function() {
+        if (ttl === 0) {
+          return { done: true, value: null };
+        } else {
+          return { done: false, value: ttl-- };
+        }
+      }
+    };
+  }
+};
+
+assert.deepEqual([3, 2, 1], [...obj]);
diff --git a/test/fixtures/transformation/esnext-es6-spread/new-object.js b/test/fixtures/transformation/esnext-es6-spread/new-object.js
new file mode 100644
index 0000000000..6e4af74279
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/new-object.js
@@ -0,0 +1,11 @@
+var callCount = 0;
+function getArray() {
+  callCount++;
+  return Array;
+}
+
+assert.deepEqual([1, 2, 3], new Array(...[1, 2, 3]));
+
+// Ensure the expression of the function being initialized is not copied.
+assert.deepEqual([1, 2, 3], new (getArray())(...[1, 2, 3]));
+assert.equal(callCount, 1);
diff --git a/test/fixtures/transformation/esnext-es6-spread/preserve-context.js b/test/fixtures/transformation/esnext-es6-spread/preserve-context.js
new file mode 100644
index 0000000000..e63f88e788
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/preserve-context.js
@@ -0,0 +1,35 @@
+var MATH = {
+  sum: function(...numbers) {
+    return numbers.reduce(this.add, 0);
+  },
+
+  add: function(a, b) {
+    return a + b;
+  }
+};
+
+assert.equal(MATH.sum(1, ...[2, 3]), 6);
+
+// Ensure that the below does not expand to this:
+//
+//   obj.getSelf().call.apply(obj.getSelf(), []);
+//
+
+var ops = [];
+var obj = {
+  getSelf: function() {
+    ops.push('getSelf');
+    return this;
+  },
+
+  doCall: function() {
+    ops.push('doCall', this);
+  }
+};
+
+obj.getSelf().doCall(...[]);
+assert.deepEqual(ops, ['getSelf', 'doCall', obj]);
+
+ops = [];
+obj['getSelf']().doCall(...[]);
+assert.deepEqual(ops, ['getSelf', 'doCall', obj]);
diff --git a/test/fixtures/transformation/esnext-es6-spread/simple-function-call.js b/test/fixtures/transformation/esnext-es6-spread/simple-function-call.js
new file mode 100644
index 0000000000..106bfa55be
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-spread/simple-function-call.js
@@ -0,0 +1,6 @@
+function sum(...numbers) {
+  return numbers.reduce(function(sum, n) { return n + sum; }, 0);
+}
+
+var numbers = [1, 2, 3];
+assert.equal(sum(...numbers), 6);
diff --git a/test/fixtures/transformation/esnext-es6-templates/multi-line.js b/test/fixtures/transformation/esnext-es6-templates/multi-line.js
new file mode 100644
index 0000000000..6d1be1c2bc
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/multi-line.js
@@ -0,0 +1,4 @@
+var s = `a
+    b
+    c`;
+assert.equal(s, 'a\n    b\n    c');
diff --git a/test/fixtures/transformation/esnext-es6-templates/nested-interpolation.js b/test/fixtures/transformation/esnext-es6-templates/nested-interpolation.js
new file mode 100644
index 0000000000..83083e9fd0
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/nested-interpolation.js
@@ -0,0 +1,4 @@
+assert.strictEqual(
+  `a${1}b${`${1+1}c`}3`,
+  'a1b2c3'
+);
diff --git a/test/fixtures/transformation/esnext-es6-templates/no-interpolation.js b/test/fixtures/transformation/esnext-es6-templates/no-interpolation.js
new file mode 100644
index 0000000000..1854b04ff5
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/no-interpolation.js
@@ -0,0 +1,2 @@
+var s = `str`;
+assert.equal(s, 'str');
diff --git a/test/fixtures/transformation/esnext-es6-templates/raw-tagged-template-expression.js b/test/fixtures/transformation/esnext-es6-templates/raw-tagged-template-expression.js
new file mode 100644
index 0000000000..831ad050ab
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/raw-tagged-template-expression.js
@@ -0,0 +1,6 @@
+function r(strings) {
+  assert.equal(strings.raw[0], '\\n');
+  return strings.raw.join('');
+}
+
+assert.equal(r `\n`, '\\n');
diff --git a/test/fixtures/transformation/esnext-es6-templates/simple-interpolation.js b/test/fixtures/transformation/esnext-es6-templates/simple-interpolation.js
new file mode 100644
index 0000000000..b96a02a543
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/simple-interpolation.js
@@ -0,0 +1,2 @@
+var s = `1 + 1 = ${1 + 1}`;
+assert.equal(s, '1 + 1 = 2');
diff --git a/test/fixtures/transformation/esnext-es6-templates/tagged-template-expression.js b/test/fixtures/transformation/esnext-es6-templates/tagged-template-expression.js
new file mode 100644
index 0000000000..5b894c55ac
--- /dev/null
+++ b/test/fixtures/transformation/esnext-es6-templates/tagged-template-expression.js
@@ -0,0 +1,26 @@
+function tag(strings) {
+  var values = [].slice.call(arguments, 1);
+  assert.equal(strings[0], 'a');
+  assert.equal(strings[1], 'b');
+  assert.equal(values[0], 42);
+  return 'whatever';
+}
+assert.equal(tag `a${ 42 }b`, 'whatever');
+
+function tagInterpolateFirst(strings) {
+  var values = [].slice.call(arguments, 1);
+  assert.equal(strings[0], '');
+  assert.equal(strings[1], 'b');
+  assert.equal(values[0], 42);
+  return 'whatever';
+}
+assert.equal(tagInterpolateFirst `${ 42 }b`, 'whatever');
+
+function tagInterpolateLast(strings) {
+  var values = [].slice.call(arguments, 1);
+  assert.equal(strings[0], 'a');
+  assert.equal(strings[1], '');
+  assert.equal(values[0], 42);
+  return 'whatever';
+}
+assert.equal(tagInterpolateLast `a${ 42 }`, 'whatever');

From 0c0f40d14a9b3300c0310475f3f54814a1a3c281 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 07:58:49 +1100
Subject: [PATCH 02/14] only automatically assume test is exec if it has a js
 extension

---
 test/_helper.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/_helper.js b/test/_helper.js
index 8273a11443..6f5afdd93b 100644
--- a/test/_helper.js
+++ b/test/_helper.js
@@ -49,7 +49,7 @@ exports.get = function (entryName) {
 
       if (fs.statSync(taskDir).isFile()) {
         var ext = path.extname(taskDir);
-        if (ext === ".json") return;
+        if (ext !== ".js") return;
 
         execLoc = taskDir;
       }

From 7f4efecb7db47821cb72ab692a7e40398b1ae054 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 07:59:43 +1100
Subject: [PATCH 03/14] support for CallExpression in
 Scope.prototype.generateUidBasedOnNode

---
 lib/6to5/traverse/scope.js                    | 47 +++++++------------
 .../accessing-super-class/expected.js         |  4 +-
 .../assignment-expression/expected.js         |  4 +-
 .../expected.js                               | 16 +++----
 .../playground/method-binding/expected.js     |  4 +-
 5 files changed, 31 insertions(+), 44 deletions(-)

diff --git a/lib/6to5/traverse/scope.js b/lib/6to5/traverse/scope.js
index f6cc050998..eaa82a51b2 100644
--- a/lib/6to5/traverse/scope.js
+++ b/lib/6to5/traverse/scope.js
@@ -63,38 +63,29 @@ Scope.prototype.generateUidBasedOnNode = function (parent, file) {
     node = parent.left;
   } else if (t.isVariableDeclarator(parent)) {
     node = parent.id;
-  }
-
-  var id = "ref";
-
-  if (t.isProperty(node)) {
+  } else if (t.isProperty(node)) {
     node = node.key;
   }
 
-  if (t.isIdentifier(node)) {
-    id = node.name;
-  } else if (t.isLiteral(node)) {
-    id = node.value;
-  } else if (t.isMemberExpression(node)) {
-    var parts = [];
+  var parts = [];
 
-    var add = function (node) {
-      if (t.isMemberExpression(node)) {
-        add(node.object);
-        add(node.property);
-      } else if (t.isIdentifier(node)) {
-        parts.push(node.name);
-      } else if (t.isLiteral(node)) {
-        parts.push(node.value);
-      }
-    };
+  var add = function (node) {
+    if (t.isMemberExpression(node)) {
+      add(node.object);
+      add(node.property);
+    } else if (t.isIdentifier(node)) {
+      parts.push(node.name);
+    } else if (t.isLiteral(node)) {
+      parts.push(node.value);
+    } else if (t.isCallExpression(node)) {
+      add(node.callee);
+    }
+  };
 
-    add(node);
+  add(node);
 
-    id = parts.join("$");
-  }
-
-  id = id.replace(/^_/, "");
+  var id = parts.join("$");
+  id = id.replace(/^_/, "") || "ref";
 
   return file.generateUidIdentifier(id, this);
 };
@@ -108,10 +99,6 @@ Scope.prototype.generateUidBasedOnNode = function (parent, file) {
  */
 
 Scope.prototype.generateTempBasedOnNode = function (node, file) {
-  if (!t.isIdentifier(node) && !t.isMemberExpression(node)) {
-    throw new TypeError("Invalid node type " + JSON.stringify(node.type) + " passed to Scope.prototype.generateTempBasedOnNode");
-  }
-
   if (t.isIdentifier(node) && this.has(node.name, true)) {
     return null;
   }
diff --git a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
index 1eec391c5e..14f12f07e2 100644
--- a/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
+++ b/test/fixtures/transformation/es6-classes/accessing-super-class/expected.js
@@ -22,8 +22,8 @@ var Test = (function () {
     _Foo.prototype.test.call(this);
     foob(_Foo);
 
-    _Foo.call.apply(null, [this].concat(_slice.call(arguments)));
-    _Foo.call.apply(null, [this, "test"].concat(_slice.call(arguments)));
+    _Foo.call.apply(_Foo, [this].concat(_slice.call(arguments)));
+    _Foo.call.apply(_Foo, [this, "test"].concat(_slice.call(arguments)));
 
     (_Foo$prototype$test = _Foo.prototype.test).call.apply(_Foo$prototype$test, [this].concat(_slice.call(arguments)));
     (_Foo$prototype$test2 = _Foo.prototype.test).call.apply(_Foo$prototype$test2, [this, "test"].concat(_slice.call(arguments)));
diff --git a/test/fixtures/transformation/optional-proto-to-assign/assignment-expression/expected.js b/test/fixtures/transformation/optional-proto-to-assign/assignment-expression/expected.js
index 6a66b4e972..9de37223a2 100644
--- a/test/fixtures/transformation/optional-proto-to-assign/assignment-expression/expected.js
+++ b/test/fixtures/transformation/optional-proto-to-assign/assignment-expression/expected.js
@@ -1,6 +1,6 @@
 "use strict";
 
-var _foo, _foo$bar, _foo2;
+var _foo, _foo$bar, _foo$bar2;
 var _defaults = function (obj, defaults) {
   for (var key in defaults) {
     if (obj[key] === undefined) {
@@ -15,4 +15,4 @@ console.log((_foo = foo, _defaults(_foo, bar), _foo));
 
 console.log((_foo$bar = foo[bar], _defaults(_foo$bar, bar), _foo$bar));
 
-console.log((_foo2 = foo[bar()], _defaults(_foo2, bar), _foo2));
+console.log((_foo$bar2 = foo[bar()], _defaults(_foo$bar2, bar), _foo$bar2));
diff --git a/test/fixtures/transformation/playground/memoization-assignment-operator/expected.js b/test/fixtures/transformation/playground/memoization-assignment-operator/expected.js
index 4d9647c912..fbb64ac4f8 100644
--- a/test/fixtures/transformation/playground/memoization-assignment-operator/expected.js
+++ b/test/fixtures/transformation/playground/memoization-assignment-operator/expected.js
@@ -1,6 +1,6 @@
 "use strict";
 
-var _obj2, _obj4, _ref2, _obj6, _ref4;
+var _obj2, _obj4, _x2, _obj$y2, _x4;
 var _hasOwn = Object.prototype.hasOwnProperty;
 var obj = {};
 
@@ -11,17 +11,17 @@ if (!_hasOwn.call(_obj, "x")) _obj.x = 2;
 console.log((_obj2 = obj, !_hasOwn.call(_obj2, "x") && (_obj2.x = 2), _obj2.x));
 
 var _obj3 = obj;
-var _ref = x();
+var _x = x();
 
-if (!_hasOwn.call(_obj3, _ref)) _obj3[_ref] = 2;
+if (!_hasOwn.call(_obj3, _x)) _obj3[_x] = 2;
 
 
-console.log((_obj4 = obj, _ref2 = x(), !_hasOwn.call(_obj4, _ref2) && (_obj4[_ref2] = 2), _obj4[_ref2]));
+console.log((_obj4 = obj, _x2 = x(), !_hasOwn.call(_obj4, _x2) && (_obj4[_x2] = 2), _obj4[_x2]));
 
-var _obj5 = obj[y()];
-var _ref3 = x();
+var _obj$y = obj[y()];
+var _x3 = x();
 
-if (!_hasOwn.call(_obj5, _ref3)) _obj5[_ref3] = 2;
+if (!_hasOwn.call(_obj$y, _x3)) _obj$y[_x3] = 2;
 
 
-console.log((_obj6 = obj[y()], _ref4 = x(), !_hasOwn.call(_obj6, _ref4) && (_obj6[_ref4] = 2), _obj6[_ref4]));
+console.log((_obj$y2 = obj[y()], _x4 = x(), !_hasOwn.call(_obj$y2, _x4) && (_obj$y2[_x4] = 2), _obj$y2[_x4]));
diff --git a/test/fixtures/transformation/playground/method-binding/expected.js b/test/fixtures/transformation/playground/method-binding/expected.js
index f103f4683f..156bcfffd5 100644
--- a/test/fixtures/transformation/playground/method-binding/expected.js
+++ b/test/fixtures/transformation/playground/method-binding/expected.js
@@ -1,11 +1,11 @@
 "use strict";
 
-var _obj, _obj2, _obj$foo, _obj$foo2, _obj3, _args, _args2, _args3;
+var _obj, _obj2, _obj$foo, _obj$foo2, _obj$foo3, _args, _args2, _args3;
 var fn = (_obj = obj, _obj.method.bind(_obj));
 var fn = (_obj2 = obj, _obj2.method.bind(_obj2, "foob"));
 var fn = (_obj$foo = obj[foo], _obj$foo.method.bind(_obj$foo));
 var fn = (_obj$foo2 = obj.foo, _obj$foo2.method.bind(_obj$foo2));
-var fn = (_obj3 = obj[foo()], _obj3.method.bind(_obj3));
+var fn = (_obj$foo3 = obj[foo()], _obj$foo3.method.bind(_obj$foo3));
 
 ["foo", "bar"].map((_args = [], function (_val) {
   return _val.toUpperCase();

From a645ae0583acbfb6115e161fd20ea66bce848e92 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 07:59:56 +1100
Subject: [PATCH 04/14] contextLiteral fallback in es6-spread transformer

---
 lib/6to5/transformation/transformers/es6-spread.js | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/6to5/transformation/transformers/es6-spread.js b/lib/6to5/transformation/transformers/es6-spread.js
index 2415cc8a8c..bde318aa6d 100644
--- a/lib/6to5/transformation/transformers/es6-spread.js
+++ b/lib/6to5/transformation/transformers/es6-spread.js
@@ -83,6 +83,8 @@ exports.CallExpression = function (node, parent, file, scope) {
     if (temp) {
       callee.object = t.assignmentExpression("=", temp, callee.object);
       contextLiteral = temp;
+    } else {
+      contextLiteral = callee.object;
     }
     t.appendToMemberExpression(callee, t.identifier("apply"));
   } else {

From 22eeae1a93762d0c38b5572a7993e76248ab94b2 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:00:40 +1100
Subject: [PATCH 05/14] use `assert` instead of `expect`

---
 .../transformation/esnext-es6-rest-parameters/arrow-fn.js    | 5 +----
 .../transformation/esnext-es6-rest-parameters/declaration.js | 5 +----
 .../transformation/esnext-es6-rest-parameters/rest.js        | 5 +----
 3 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js b/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
index 34c96f5ecb..eb9d8ea8c5 100644
--- a/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/arrow-fn.js
@@ -1,8 +1,5 @@
-/* jshint esnext: true */
-/* global expect */
-
 var join = (joinStr, ...items) => {
   return items.join(joinStr);
 };
 
-expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
+assert.deepEqual(join(' ', 'a', 'b', 'c'), 'a b c');
diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js b/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
index 1cc45ac46f..2d3ca5d283 100644
--- a/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/declaration.js
@@ -1,8 +1,5 @@
-/* jshint esnext: true */
-/* global expect */
-
 function join(joinStr, ...items) {
   return items.join(joinStr);
 }
 
-expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
+assert.deepEqual(join(' ', 'a', 'b', 'c'), 'a b c');
diff --git a/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js b/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
index 9d0e63e85d..769bf2d2a4 100644
--- a/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
+++ b/test/fixtures/transformation/esnext-es6-rest-parameters/rest.js
@@ -1,8 +1,5 @@
-/* jshint esnext: true */
-/* global expect */
-
 var join = function(joinStr, ...items) {
   return items.join(joinStr);
 };
 
-expect(join(' ', 'a', 'b', 'c')).to.equal('a b c');
+assert.deepEqual(join(' ', 'a', 'b', 'c'), 'a b c');

From 7ab6df093bad0ecf1af24df65465b23634566410 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:00:49 +1100
Subject: [PATCH 06/14] use `Symbol.iterator` instead of `@@iterator`

---
 test/fixtures/transformation/esnext-es6-spread/iterator.js | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/test/fixtures/transformation/esnext-es6-spread/iterator.js b/test/fixtures/transformation/esnext-es6-spread/iterator.js
index 438e7564de..6e5ef15ba2 100644
--- a/test/fixtures/transformation/esnext-es6-spread/iterator.js
+++ b/test/fixtures/transformation/esnext-es6-spread/iterator.js
@@ -1,8 +1,5 @@
-function Symbol() {}
-Symbol.iterator = '@@iterator';
-
 var obj = {
-  '@@iterator': function() {
+  [Symbol.iterator]: function() {
     var ttl = 3;
     return {
       next: function() {

From 4506e39cf5eb68898c5e58f9df77c66ff5433df0 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:01:08 +1100
Subject: [PATCH 07/14] add `toString` key to instance keys as methods are
 enumerable

---
 test/fixtures/transformation/esnext-es6-classes/enumerable.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/fixtures/transformation/esnext-es6-classes/enumerable.js b/test/fixtures/transformation/esnext-es6-classes/enumerable.js
index fe5c02d113..392fda2ca9 100644
--- a/test/fixtures/transformation/esnext-es6-classes/enumerable.js
+++ b/test/fixtures/transformation/esnext-es6-classes/enumerable.js
@@ -17,4 +17,4 @@ for (var key in point) {
 }
 
 assert.equal(point.toString(), '(1, 2)');
-assert.deepEqual(keys.sort(), ['x', 'y']);
+assert.deepEqual(keys.sort(), ['toString', 'x', 'y']);

From dea73b7186526c86a33563be95c4b211c5037814 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:01:29 +1100
Subject: [PATCH 08/14] change code assertion to 6to5 output

---
 .../does-not-bind-this-from-standard-function.js            | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js b/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
index c2eeddcc3e..6f3ffee93a 100644
--- a/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
+++ b/test/fixtures/transformation/esnext-es6-arrow-functions/does-not-bind-this-from-standard-function.js
@@ -1,5 +1,5 @@
-var dynamicThisGetter = () => function(){ return this; };
+var dynamicThisGetter = () => function () { return this; };
 assert.equal(
-  normalize('('+dynamicThisGetter.toString()+')'),
-  normalize('(function(){ return function(){ return this; }; })')
+  '(' + dynamicThisGetter.toString() + ')',
+  '(function () {\n  return function () {\n    return this;\n  };\n})'
 );

From c578db7ae8d46ea343e6e69f73af8338c0b26309 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:34:14 +1100
Subject: [PATCH 09/14] upgrade acorn-6to5

---
 package.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/package.json b/package.json
index 633a6517ee..e5b3f41b53 100644
--- a/package.json
+++ b/package.json
@@ -39,7 +39,7 @@
     "test": "make test"
   },
   "dependencies": {
-    "acorn-6to5": "0.11.1-4",
+    "acorn-6to5": "0.11.1-5",
     "ast-types": "~0.6.1",
     "chokidar": "0.11.1",
     "commander": "2.5.0",

From 4d5861cfdc39d85c415da41549df7fea0d4174e6 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:34:25 +1100
Subject: [PATCH 10/14] remove invalid strict-mode es6 next class test

---
 .../esnext-es6-classes/strict-mode.js         | 23 -------------------
 1 file changed, 23 deletions(-)
 delete mode 100644 test/fixtures/transformation/esnext-es6-classes/strict-mode.js

diff --git a/test/fixtures/transformation/esnext-es6-classes/strict-mode.js b/test/fixtures/transformation/esnext-es6-classes/strict-mode.js
deleted file mode 100644
index d3ece2608e..0000000000
--- a/test/fixtures/transformation/esnext-es6-classes/strict-mode.js
+++ /dev/null
@@ -1,23 +0,0 @@
-class StrictModeTest {
-  test() {
-    var implicitThisInsideClassBody = (function() {
-      return this;
-    })();
-    assert.strictEqual(
-      implicitThisInsideClassBody,
-      undefined,
-      'implicit `this` inside class body is undefined'
-    );
-  }
-}
-
-new StrictModeTest().test();
-
-var implicitThisOutsideClass = (function() {
-  return this;
-})();
-assert.notStrictEqual(
-  implicitThisOutsideClass,
-  undefined,
-  'implicit `this` outside class body is not undefined'
-);

From cbcad22d81c9d342dbfcbc99f4abde10861ff9ef Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:35:14 +1100
Subject: [PATCH 11/14] update default parameters transformer to use `var a =
 arguments[0] === undefined ? 1 : arguments[0];` instead of `if (a ===
 undefined) a = 1;`

---
 .../templates/default-parameter.js            |  1 +
 .../templates/if-undefined-set-to.js          |  1 -
 .../transformers/es6-default-parameters.js    | 21 +++++++++++++++----
 .../default-parameters/expected.js            |  4 ++--
 .../multiple/expected.js                      | 10 ++++-----
 .../es6-default-parameters/single/expected.js |  4 ++--
 6 files changed, 27 insertions(+), 14 deletions(-)
 create mode 100644 lib/6to5/transformation/templates/default-parameter.js
 delete mode 100644 lib/6to5/transformation/templates/if-undefined-set-to.js

diff --git a/lib/6to5/transformation/templates/default-parameter.js b/lib/6to5/transformation/templates/default-parameter.js
new file mode 100644
index 0000000000..74fecfd0f2
--- /dev/null
+++ b/lib/6to5/transformation/templates/default-parameter.js
@@ -0,0 +1 @@
+var VARIABLE_NAME = ARGUMENTS[ARGUMENT_KEY] === undefined ? DEFAULT_VALUE : ARGUMENTS[ARGUMENT_KEY];
diff --git a/lib/6to5/transformation/templates/if-undefined-set-to.js b/lib/6to5/transformation/templates/if-undefined-set-to.js
deleted file mode 100644
index c5ed82cdf9..0000000000
--- a/lib/6to5/transformation/templates/if-undefined-set-to.js
+++ /dev/null
@@ -1 +0,0 @@
-if (VARIABLE === undefined) VARIABLE = DEFAULT;
diff --git a/lib/6to5/transformation/transformers/es6-default-parameters.js b/lib/6to5/transformation/transformers/es6-default-parameters.js
index 9715c2bbdc..ba3c0ad631 100644
--- a/lib/6to5/transformation/transformers/es6-default-parameters.js
+++ b/lib/6to5/transformation/transformers/es6-default-parameters.js
@@ -49,16 +49,29 @@ exports.Function = function (node, parent, file, scope) {
 
   var body = [];
 
+  var argsIdentifier = t.identifier("arguments");
+  argsIdentifier._ignoreAliasFunctions = true;
+
+  var lastNonDefaultParam = 0;
+
   for (i in node.defaults) {
     def = node.defaults[i];
-    if (!def) continue;
+    if (!def) {
+      lastNonDefaultParam = +i + 1;
+      continue;
+    }
 
-    body.push(util.template("if-undefined-set-to", {
-      VARIABLE: node.params[i],
-      DEFAULT:  def
+    body.push(util.template("default-parameter", {
+      VARIABLE_NAME: node.params[i],
+      DEFAULT_VALUE: def,
+      ARGUMENT_KEY:  t.literal(+i),
+      ARGUMENTS:     argsIdentifier
     }, true));
   }
 
+  // we need to cut off all trailing default parameters
+  node.params = node.params.slice(0, lastNonDefaultParam);
+
   if (iife) {
     var container = t.functionExpression(null, [], node.body, node.generator);
     container._aliasFunction = true;
diff --git a/test/fixtures/transformation/es6-arrow-functions/default-parameters/expected.js b/test/fixtures/transformation/es6-arrow-functions/default-parameters/expected.js
index baba36b081..19d93a94d6 100644
--- a/test/fixtures/transformation/es6-arrow-functions/default-parameters/expected.js
+++ b/test/fixtures/transformation/es6-arrow-functions/default-parameters/expected.js
@@ -1,7 +1,7 @@
 "use strict";
 
-var some = function (count) {
-  if (count === undefined) count = "30";
+var some = function () {
+  var count = arguments[0] === undefined ? "30" : arguments[0];
   console.log("count", count);
 };
 
diff --git a/test/fixtures/transformation/es6-default-parameters/multiple/expected.js b/test/fixtures/transformation/es6-default-parameters/multiple/expected.js
index 55bc52c5c9..af684c28f7 100644
--- a/test/fixtures/transformation/es6-default-parameters/multiple/expected.js
+++ b/test/fixtures/transformation/es6-default-parameters/multiple/expected.js
@@ -1,12 +1,12 @@
 "use strict";
 
-var t = function (t, f) {
-  if (t === undefined) t = "foo";
-  if (f === undefined) f = 5;
+var t = function () {
+  var t = arguments[0] === undefined ? "foo" : arguments[0];
+  var f = arguments[1] === undefined ? 5 : arguments[1];
   return t + " bar " + f;
 };
 
-var a = function (t, f) {
-  if (f === undefined) f = 5;
+var a = function (t) {
+  var f = arguments[1] === undefined ? 5 : arguments[1];
   return t + " bar " + f;
 };
diff --git a/test/fixtures/transformation/es6-default-parameters/single/expected.js b/test/fixtures/transformation/es6-default-parameters/single/expected.js
index 5021d6e0ab..f953c7a0a9 100644
--- a/test/fixtures/transformation/es6-default-parameters/single/expected.js
+++ b/test/fixtures/transformation/es6-default-parameters/single/expected.js
@@ -1,6 +1,6 @@
 "use strict";
 
-var t = function (t) {
-  if (t === undefined) t = "foo";
+var t = function () {
+  var t = arguments[0] === undefined ? "foo" : arguments[0];
   return t + " bar";
 };

From 9a2fd22e91983f046adcdc44530cbd65b7a7433d Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 08:35:28 +1100
Subject: [PATCH 12/14] add newline to esnext super change proto test

---
 .../transformation/esnext-es6-classes/super-change-proto.js      | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js b/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
index d0012cfc0b..f7c653b460 100644
--- a/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
+++ b/test/fixtures/transformation/esnext-es6-classes/super-change-proto.js
@@ -7,6 +7,7 @@ class Base {
 class OtherBase {
   p() { log += '[OtherBase]'; }
 }
+
 class Derived extends Base {
   p() {
     log += '[Derived]';

From 35fda899a8cf993398adff3dae874d453c56dbd1 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 15:30:40 +1100
Subject: [PATCH 13/14] remove spec-no-duplicate-properties transformer

---
 lib/6to5/transformation/transform.js          |  1 -
 .../spec-no-duplicate-properties.js           | 25 -------------------
 2 files changed, 26 deletions(-)
 delete mode 100644 lib/6to5/transformation/transformers/spec-no-duplicate-properties.js

diff --git a/lib/6to5/transformation/transform.js b/lib/6to5/transformation/transform.js
index e78a0ea3b1..bf647e1f69 100644
--- a/lib/6to5/transformation/transform.js
+++ b/lib/6to5/transformation/transform.js
@@ -42,7 +42,6 @@ _.each({
   // spec
   specBlockHoistFunctions:   require("./transformers/spec-block-hoist-functions"),
   specNoForInOfAssignment:   require("./transformers/spec-no-for-in-of-assignment"),
-  specNoDuplicateProperties: require("./transformers/spec-no-duplicate-properties"),
 
   // playground
   methodBinding:             require("./transformers/playground-method-binding"),
diff --git a/lib/6to5/transformation/transformers/spec-no-duplicate-properties.js b/lib/6to5/transformation/transformers/spec-no-duplicate-properties.js
deleted file mode 100644
index 6c7e93e761..0000000000
--- a/lib/6to5/transformation/transformers/spec-no-duplicate-properties.js
+++ /dev/null
@@ -1,25 +0,0 @@
-var t = require("../../types");
-
-exports.ObjectExpression = function (node, parent, file) {
-  var keys = [];
-
-  for (var i in node.properties) {
-    var prop = node.properties[i];
-    if (prop.computed || prop.kind !== "init") continue;
-
-    var key = prop.key;
-    if (t.isIdentifier(key)) {
-      key = key.name;
-    } else if (t.isLiteral(key)) {
-      key = key.value;
-    } else {
-      continue;
-    }
-
-    if (keys.indexOf(key) >= 0) {
-      throw file.errorWithNode(prop.key, "Duplicate property key");
-    } else {
-      keys.push(key);
-    }
-  }
-};

From ccabb91f6932bcd51212dbb0ad3a766806136baf Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 4 Jan 2015 15:30:59 +1100
Subject: [PATCH 14/14] add back deleted object-define-properties-closure
 template

---
 .../templates/object-define-properties-closure.js            | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 lib/6to5/transformation/templates/object-define-properties-closure.js

diff --git a/lib/6to5/transformation/templates/object-define-properties-closure.js b/lib/6to5/transformation/templates/object-define-properties-closure.js
new file mode 100644
index 0000000000..a4e51eaf06
--- /dev/null
+++ b/lib/6to5/transformation/templates/object-define-properties-closure.js
@@ -0,0 +1,5 @@
+
+(function (KEY) {
+  CONTENT;
+  return KEY;
+})(OBJECT);