diff --git a/test/built-ins/WeakMap/prototype/set/adds-element.js b/test/built-ins/WeakMap/prototype/set/adds-element.js
new file mode 100644
index 0000000000000000000000000000000000000000..0b0d86f63e4d20ddc9d2576fa515cf87dc8e6871
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/adds-element.js
@@ -0,0 +1,27 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Appends value as the last element of entries.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  7. Let p be the Record {[[key]]: key, [[value]]: value}.
+  8. Append p as the last element of entries.
+  ...
+---*/
+
+var map = new WeakMap();
+var foo = {};
+var bar = {};
+var baz = {};
+
+map.set(foo, 1);
+map.set(bar, 2);
+map.set(baz, 3);
+
+assert(map.has(foo));
+assert(map.has(bar));
+assert(map.has(baz));
diff --git a/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-array.js b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-array.js
new file mode 100644
index 0000000000000000000000000000000000000000..b98e11d2fda6fd2fa07f9476d88c2b6677350260
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-array.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Throws TypeError if `this` doesn't have a [[WeakMapData]] internal slot.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError
+  exception.
+  ...
+
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call([], {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call([], {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-map.js b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-map.js
new file mode 100644
index 0000000000000000000000000000000000000000..b17dbc7f63e749ee9ab27283630b3429bd4c4ed0
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-map.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Throws TypeError if `this` doesn't have a [[WeakMapData]] internal slot.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError
+  exception.
+  ...
+features: [Map]
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(new Map(), {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(new Map(), {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-object.js b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-object.js
new file mode 100644
index 0000000000000000000000000000000000000000..5adc57bc5946acf2ab9d5cd881478efb8cfda294
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-object.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Throws TypeError if `this` doesn't have a [[WeakMapData]] internal slot.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError
+  exception.
+  ...
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call({}, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call({}, {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-set.js b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-set.js
new file mode 100644
index 0000000000000000000000000000000000000000..0ef36a59371abb605399a37eaa0bc37e1d86ce30
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-set.js
@@ -0,0 +1,24 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Throws TypeError if `this` doesn't have a [[WeakMapData]] internal slot.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError
+  exception.
+  ...
+features: [Set]
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(new Set(), {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(new Set(), {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-weakmap-prototype.js b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-weakmap-prototype.js
new file mode 100644
index 0000000000000000000000000000000000000000..59d4308dde8b85072751146d3f48ad6cddfcbc74
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/does-not-have-weakmapdata-internal-slot-weakmap-prototype.js
@@ -0,0 +1,23 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: >
+  Throws TypeError if `this` doesn't have a [[WeakMapData]] internal slot.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  ...
+  3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError
+  exception.
+  ...
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(WeakMap.prototype, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(WeakMap.prototype, {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/key-not-object-throw.js b/test/built-ins/WeakMap/prototype/set/key-not-object-throw.js
new file mode 100644
index 0000000000000000000000000000000000000000..4b4031d1c58433f6d80bebfccd506e2f0a74da75
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/key-not-object-throw.js
@@ -0,0 +1,37 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `key` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  5. If Type(key) is not Object, throw a TypeError exception.
+features: [Symbol]
+---*/
+
+var s = new WeakMap();
+
+assert.throws(TypeError, function() {
+  s.set(1, 1);
+});
+
+assert.throws(TypeError, function() {
+  s.set(false, 1);
+});
+
+assert.throws(TypeError, function() {
+  s.set(undefined, 1);
+});
+
+assert.throws(TypeError, function() {
+  s.set('string', 1);
+});
+
+assert.throws(TypeError, function() {
+  s.set(null, 1);
+});
+
+assert.throws(TypeError, function() {
+  s.set(Symbol(), 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/length.js b/test/built-ins/WeakMap/prototype/set/length.js
new file mode 100644
index 0000000000000000000000000000000000000000..0d687e51f21fda4ac3428a24cd14b571331d6644
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/length.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: WeakMap.prototype.set.length descriptor
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  WeakMap.prototype.set.length, 2,
+  'The value of `WeakMap.prototype.set.length` is `2`'
+);
+
+verifyNotEnumerable(WeakMap.prototype.set, 'length');
+verifyNotWritable(WeakMap.prototype.set, 'length');
+verifyConfigurable(WeakMap.prototype.set, 'length');
diff --git a/test/built-ins/WeakMap/prototype/set/name.js b/test/built-ins/WeakMap/prototype/set/name.js
new file mode 100644
index 0000000000000000000000000000000000000000..9c4f63080fe4ccd8d6974908702d1a47573992bf
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/name.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: WeakMap.prototype.set.name descriptor
+info: >
+  WeakMap.prototype.set ( value )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  WeakMap.prototype.set.name, 'set',
+  'The value of WeakMap.prototype.set.name is "set"'
+);
+
+verifyNotEnumerable(WeakMap.prototype.set, 'name');
+verifyNotWritable(WeakMap.prototype.set, 'name');
+verifyConfigurable(WeakMap.prototype.set, 'name');
diff --git a/test/built-ins/WeakMap/prototype/set/returns-this-when-ignoring-duplicate.js b/test/built-ins/WeakMap/prototype/set/returns-this-when-ignoring-duplicate.js
new file mode 100644
index 0000000000000000000000000000000000000000..b7221250469dd1a3178c2fca14cd2977969a24a4
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/returns-this-when-ignoring-duplicate.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Returns `this` when new value is duplicate.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  ...
+  6. Repeat for each Record {[[key]], [[value]]} p that is an element of
+  entries,
+    a. If p.[[key]] is not empty and SameValue(p.[[key]], key) is true, then
+      i. Set p.[[value]] to value.
+      ii. Return M.
+  ...
+---*/
+
+var foo = {};
+var map = new WeakMap([[foo, 1]]);
+
+assert.sameValue(map.set(foo, 1), map, '`map.set(foo, 1)` returns `map`');
diff --git a/test/built-ins/WeakMap/prototype/set/returns-this.js b/test/built-ins/WeakMap/prototype/set/returns-this.js
new file mode 100644
index 0000000000000000000000000000000000000000..d92c5fc801973e92ea9d5b76ccf8315f54f62a73
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/returns-this.js
@@ -0,0 +1,17 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Returns `this` after setting a new value.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be this value.
+  ...
+  9. Return M.
+
+---*/
+
+var map = new WeakMap();
+
+assert.sameValue(map.set({}, 1), map, '`map.set({}, 1)` returns `map`');
diff --git a/test/built-ins/WeakMap/prototype/set/set.js b/test/built-ins/WeakMap/prototype/set/set.js
new file mode 100644
index 0000000000000000000000000000000000000000..173b3e0ebf122f36291dc7ad2eeb9a3f70a9cc97
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/set.js
@@ -0,0 +1,22 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: WeakMap.prototype.set property descriptor
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+  typeof WeakMap.prototype.set,
+  'function',
+  'typeof WeakMap.prototype.set is "function"'
+);
+
+verifyNotEnumerable(WeakMap.prototype, 'set');
+verifyWritable(WeakMap.prototype, 'set');
+verifyConfigurable(WeakMap.prototype, 'set');
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-boolean.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-boolean.js
new file mode 100644
index 0000000000000000000000000000000000000000..e36b6201e7e577f075486027e0078786fab53fe3
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-boolean.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(false, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(false, {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-null.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-null.js
new file mode 100644
index 0000000000000000000000000000000000000000..dba5205606adf3df32d4ce8925559b4980d00d9a
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-null.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(null, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(null, {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-number.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-number.js
new file mode 100644
index 0000000000000000000000000000000000000000..e4745ca50e50b3367cbacc425c67e34ace8618e6
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-number.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(0, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(0, {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-string.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-string.js
new file mode 100644
index 0000000000000000000000000000000000000000..8764b24258ac6c9537809f440d9c1c1195ccea11
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-string.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call('', {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call('', {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-symbol.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-symbol.js
new file mode 100644
index 0000000000000000000000000000000000000000..c7f1cfe453808cd90da21bb80befd148bb79006f
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-symbol.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+features: [Symbol]
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(Symbol(), {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(Symbol(), {}, 1);
+});
diff --git a/test/built-ins/WeakMap/prototype/set/this-not-object-throw-undefined.js b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-undefined.js
new file mode 100644
index 0000000000000000000000000000000000000000..4c8d0fdfff9cbbb6fe59f0d7260fd29de3028c98
--- /dev/null
+++ b/test/built-ins/WeakMap/prototype/set/this-not-object-throw-undefined.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 23.3.3.5
+description: Throws TypeError if `this` is not Object.
+info: >
+  WeakMap.prototype.set ( key, value )
+
+  1. Let M be the this value.
+  2. If Type(M) is not Object, throw a TypeError exception.
+---*/
+
+assert.throws(TypeError, function() {
+  WeakMap.prototype.set.call(undefined, {}, 1);
+});
+
+assert.throws(TypeError, function() {
+  var map = new WeakMap();
+  map.set.call(undefined, {}, 1);
+});