From 7b1eddf6b06fe0699089c6360e595d01b4093940 Mon Sep 17 00:00:00 2001
From: Leonardo Balter <leonardo.balter@gmail.com>
Date: Thu, 30 Jun 2016 15:05:47 -0300
Subject: [PATCH] Update and expand tests for isNaN

---
 test/built-ins/isNaN/S15.1.2.4_A1_T1.js       | 70 ------------------
 test/built-ins/isNaN/S15.1.2.4_A1_T2.js       | 40 ----------
 test/built-ins/isNaN/S15.1.2.4_A2.1.js        | 25 -------
 test/built-ins/isNaN/S15.1.2.4_A2.2.js        | 25 -------
 test/built-ins/isNaN/S15.1.2.4_A2.3.js        | 16 ----
 test/built-ins/isNaN/S15.1.2.4_A2.4.js        | 13 ----
 test/built-ins/isNaN/S15.1.2.4_A2.5.js        | 25 -------
 test/built-ins/isNaN/length.js                | 16 ++++
 test/built-ins/isNaN/prop-desc.js             | 14 ++++
 ...turn-abrupt-from-tonumber-number-symbol.js | 20 +++++
 .../return-abrupt-from-tonumber-number.js     | 33 +++++++++
 .../isNaN/return-false-not-nan-numbers.js     | 28 +++++++
 test/built-ins/isNaN/return-true-nan.js       | 19 +++++
 test/built-ins/isNaN/tonumber-operations.js   | 28 +++++++
 .../isNaN/toprimitive-call-abrupt.js          | 30 ++++++++
 .../built-ins/isNaN/toprimitive-get-abrupt.js | 29 ++++++++
 .../isNaN/toprimitive-not-callable-throws.js  | 53 ++++++++++++++
 .../toprimitive-result-is-object-throws.js    | 32 ++++++++
 .../toprimitive-result-is-symbol-throws.js    | 36 +++++++++
 .../isNaN/toprimitive-valid-result.js         | 73 +++++++++++++++++++
 20 files changed, 411 insertions(+), 214 deletions(-)
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A1_T1.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A1_T2.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A2.1.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A2.2.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A2.3.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A2.4.js
 delete mode 100644 test/built-ins/isNaN/S15.1.2.4_A2.5.js
 create mode 100644 test/built-ins/isNaN/length.js
 create mode 100644 test/built-ins/isNaN/prop-desc.js
 create mode 100644 test/built-ins/isNaN/return-abrupt-from-tonumber-number-symbol.js
 create mode 100644 test/built-ins/isNaN/return-abrupt-from-tonumber-number.js
 create mode 100644 test/built-ins/isNaN/return-false-not-nan-numbers.js
 create mode 100644 test/built-ins/isNaN/return-true-nan.js
 create mode 100644 test/built-ins/isNaN/tonumber-operations.js
 create mode 100644 test/built-ins/isNaN/toprimitive-call-abrupt.js
 create mode 100644 test/built-ins/isNaN/toprimitive-get-abrupt.js
 create mode 100644 test/built-ins/isNaN/toprimitive-not-callable-throws.js
 create mode 100644 test/built-ins/isNaN/toprimitive-result-is-object-throws.js
 create mode 100644 test/built-ins/isNaN/toprimitive-result-is-symbol-throws.js
 create mode 100644 test/built-ins/isNaN/toprimitive-valid-result.js

diff --git a/test/built-ins/isNaN/S15.1.2.4_A1_T1.js b/test/built-ins/isNaN/S15.1.2.4_A1_T1.js
deleted file mode 100644
index 7280a328d4..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A1_T1.js
+++ /dev/null
@@ -1,70 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: >
-    isNaN applies ToNumber to its argument, then return true if the result is
-    NaN, and otherwise return false
-es5id: 15.1.2.4_A1_T1
-description: Checking all primitive
----*/
-
-// CHECK#1
-if (!(isNaN(NaN) === true)) {
-	$ERROR('#1: NaN === Not-a-Number. Actual: ' + (NaN)); 
-}
-
-// CHECK#2
-if (!(isNaN(Number.NaN) === true)) {
-	$ERROR('#2: Number.NaN === Not-a-Number. Actual: ' + (Number.NaN)); 
-}
-
-// CHECK#3
-if (!(isNaN(Number(void 0)) === true)) {
-	$ERROR('#3: Number(void 0) === Not-a-Number. Actual: ' + (Number(void 0))); 
-}
-
-// CHECK#4
-if (!(isNaN(void 0) === true)) {
-	$ERROR('#4: void 0 === Not-a-Number. Actual: ' + (void 0)); 
-}
-
-// CHECK#5
-if (!(isNaN("string") === true)) {
-	$ERROR('#5: "string" === Not-a-Number. Actual: ' + ("string")); 
-}
-
-// CHECK#6
-if (isNaN(Number.POSITIVE_INFINITY) === true) {
-	$ERROR('#6: Number.POSITIVE_INFINITY !== Not-a-Number'); 
-}
-
-// CHECK#7
-if (isNaN(Number.NEGATIVE_INFINITY) === true) {
-	$ERROR('#7: Number.NEGATIVE_INFINITY !== Not-a-Number'); 
-}
-
-// CHECK#8
-if (isNaN(Number.MAX_VALUE) === true) {
-	$ERROR('#8: Number.MAX_VALUE !== Not-a-Number'); 
-}
-
-// CHECK#9
-if (isNaN(Number.MIN_VALUE) === true) {
-	$ERROR('#9: Number.MIN_VALUE !== Not-a-Number'); 
-}
-
-// CHECK#10
-if (isNaN(-0) === true) {
-	$ERROR('#10: -0 !== Not-a-Number'); 
-}
-
-// CHECK#11
-if (isNaN(true) === true) {
-  $ERROR('#11: true !== Not-a-Number'); 
-}
-
-// CHECK#12
-if (isNaN("1") === true) {
-  $ERROR('#12: "1" !== Not-a-Number'); 
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A1_T2.js b/test/built-ins/isNaN/S15.1.2.4_A1_T2.js
deleted file mode 100644
index 34bb54409e..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A1_T2.js
+++ /dev/null
@@ -1,40 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: >
-    isNaN applies ToNumber to its argument, then return true if the result is
-    NaN, and otherwise return false
-es5id: 15.1.2.4_A1_T2
-description: Checking all object
----*/
-
-// CHECK#1
-if (!(isNaN({}) === true)) {
-	$ERROR('#1: {} === Not-a-Number. Actual: ' + ({})); 
-}
-
-// CHECK#2
-if (!(isNaN(new String("string")) === true)) {
-	$ERROR('#2: new String("string") === Not-a-Number. Actual: ' + (new String("string"))); 
-}
-
-// CHECK#3
-if (isNaN(new String("1")) === true) {
-  $ERROR('#3: new String("1") === Not-a-Number. Actual: ' + (new String("1"))); 
-}
-
-// CHECK#4
-if (isNaN(new Number(1)) === true) {
-	$ERROR('#4: new Number(1) !== Not-a-Number'); 
-}
-
-// CHECK#5
-if (!(isNaN(new Number(NaN)) === true)) {
-  $ERROR('#5: new Number(NaN) === Not-a-Number. Actual: ' + (new Number(NaN))); 
-}
-
-// CHECK#6
-if (isNaN(new Boolean(true)) === true) {
-  $ERROR('#6: new Boolean(true) !== Not-a-Number'); 
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A2.1.js b/test/built-ins/isNaN/S15.1.2.4_A2.1.js
deleted file mode 100644
index 820f918b71..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A2.1.js
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The length property of isNaN has the attribute DontEnum
-es5id: 15.1.2.4_A2.1
-description: Checking use propertyIsEnumerable, for-in
----*/
-
-//CHECK#1
-if (isNaN.propertyIsEnumerable('length') !== false) {
-  $ERROR('#1: isNaN.propertyIsEnumerable(\'length\') === false. Actual: ' + (isNaN.propertyIsEnumerable('length')));
-}
-
-//CHECK#2
-var result = true;
-for (var p in isNaN){
-  if (p === "length") {
-    result = false;
-  }  
-}
-
-if (result !== true) {
-  $ERROR('#2: result = true; for (p in isNaN) { if (p === "length") result = false; }  result === true;');
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A2.2.js b/test/built-ins/isNaN/S15.1.2.4_A2.2.js
deleted file mode 100644
index 0ce5cf3be5..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A2.2.js
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The length property of isNaN does not have the attribute DontDelete
-es5id: 15.1.2.4_A2.2
-description: Checking use hasOwnProperty, delete
----*/
-
-//CHECK#1
-if (isNaN.hasOwnProperty('length') !== true) {
-  $ERROR('#1: isNaN.hasOwnProperty(\'length\') === true. Actual: ' + (isNaN.hasOwnProperty('length')));
-}
-
-delete isNaN.length;
-
-//CHECK#2
-if (isNaN.hasOwnProperty('length') !== false) {
-  $ERROR('#2: delete isNaN.length; isNaN.hasOwnProperty(\'length\') === false. Actual: ' + (isNaN.hasOwnProperty('length')));
-}
-
-//CHECK#3
-if (isNaN.length === undefined) {
-  $ERROR('#3: delete isNaN.length; isNaN.length !== undefined');
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A2.3.js b/test/built-ins/isNaN/S15.1.2.4_A2.3.js
deleted file mode 100644
index 99efe94e3f..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A2.3.js
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The length property of isNaN has the attribute ReadOnly
-es5id: 15.1.2.4_A2.3
-description: Checking if varying the length property fails
-includes: [propertyHelper.js]
----*/
-
-//CHECK#1
-var x = isNaN.length;
-verifyNotWritable(isNaN, "length", null, Infinity);
-if (isNaN.length !== x) {
-  $ERROR('#1: x = isNaN.length; isNaN.length = Infinity; isNaN.length === x. Actual: ' + (isNaN.length));
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A2.4.js b/test/built-ins/isNaN/S15.1.2.4_A2.4.js
deleted file mode 100644
index c485ce45cc..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A2.4.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The length property of isNaN is 1
-es5id: 15.1.2.4_A2.4
-description: isNaN.length === 1
----*/
-
-//CHECK#1
-if (isNaN.length !== 1) {
-  $ERROR('#1: isNaN.length === 1. Actual: ' + (isNaN.length));
-}
diff --git a/test/built-ins/isNaN/S15.1.2.4_A2.5.js b/test/built-ins/isNaN/S15.1.2.4_A2.5.js
deleted file mode 100644
index 645cd549f5..0000000000
--- a/test/built-ins/isNaN/S15.1.2.4_A2.5.js
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2009 the Sputnik authors.  All rights reserved.
-// This code is governed by the BSD license found in the LICENSE file.
-
-/*---
-info: The isNaN property has the attribute DontEnum
-es5id: 15.1.2.4_A2.5
-description: Checking use propertyIsEnumerable, for-in
----*/
-
-//CHECK#1
-if (this.propertyIsEnumerable('isNaN') !== false) {
-  $ERROR('#1: this.propertyIsEnumerable(\'isNaN\') === false. Actual: ' + (this.propertyIsEnumerable('isNaN')));
-}
-
-//CHECK#2
-var result = true;
-for (var p in this){
-  if (p === "isNaN") {
-    result = false;
-  }  
-}
-
-if (result !== true) {
-  $ERROR('#2: result = true; for (p in this) { if (p === "isNaN") result = false; }  result === true;');
-}
diff --git a/test/built-ins/isNaN/length.js b/test/built-ins/isNaN/length.js
new file mode 100644
index 0000000000..a35ae0f5d0
--- /dev/null
+++ b/test/built-ins/isNaN/length.js
@@ -0,0 +1,16 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  The length property of isNaN is 1
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(isNaN.length, 1, "The value of `isNaN.length` is `1`");
+
+verifyNotEnumerable(isNaN, "length");
+verifyNotWritable(isNaN, "length");
+verifyConfigurable(isNaN, "length");
diff --git a/test/built-ins/isNaN/prop-desc.js b/test/built-ins/isNaN/prop-desc.js
new file mode 100644
index 0000000000..3228f1824e
--- /dev/null
+++ b/test/built-ins/isNaN/prop-desc.js
@@ -0,0 +1,14 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Property descriptor for isNaN
+includes: [propertyHelper.js]
+---*/
+
+verifyNotEnumerable(this, "isNaN");
+verifyWritable(this, "isNaN");
+verifyConfigurable(this, "isNaN");
diff --git a/test/built-ins/isNaN/return-abrupt-from-tonumber-number-symbol.js b/test/built-ins/isNaN/return-abrupt-from-tonumber-number-symbol.js
new file mode 100644
index 0000000000..cfacbf8e71
--- /dev/null
+++ b/test/built-ins/isNaN/return-abrupt-from-tonumber-number-symbol.js
@@ -0,0 +1,20 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Throws a TypeError if number is a Symbol
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+features: [Symbol]
+---*/
+
+var s = Symbol(1);
+
+assert.throws(TypeError, function() {
+  isNaN(s);
+});
diff --git a/test/built-ins/isNaN/return-abrupt-from-tonumber-number.js b/test/built-ins/isNaN/return-abrupt-from-tonumber-number.js
new file mode 100644
index 0000000000..b4f062bd88
--- /dev/null
+++ b/test/built-ins/isNaN/return-abrupt-from-tonumber-number.js
@@ -0,0 +1,33 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Return abrupt completion from ToNumber(number)
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+---*/
+
+var obj1 = {
+  valueOf: function() {
+    throw new Test262Error();
+  }
+};
+
+var obj2 = {
+  toString: function() {
+    throw new Test262Error();
+  }
+};
+
+assert.throws(Test262Error, function() {
+  isNaN(obj1);
+}, "valueOf");
+
+assert.throws(Test262Error, function() {
+  isNaN(obj2);
+}, "toString");
diff --git a/test/built-ins/isNaN/return-false-not-nan-numbers.js b/test/built-ins/isNaN/return-false-not-nan-numbers.js
new file mode 100644
index 0000000000..cf9c9bef55
--- /dev/null
+++ b/test/built-ins/isNaN/return-false-not-nan-numbers.js
@@ -0,0 +1,28 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Return false if number is not NaN
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+  2. If num is NaN, return true.
+  3. Otherwise, return false.
+---*/
+
+assert.sameValue(isNaN(0), false, "0");
+assert.sameValue(isNaN(-0), false, "-0");
+assert.sameValue(isNaN(Math.pow(2, 53)), false, "Math.pow(2, 53)");
+assert.sameValue(isNaN(-Math.pow(2, 53)), false, "-Math.pow(2, 53)");
+assert.sameValue(isNaN(1), false, "1");
+assert.sameValue(isNaN(-1), false, "-1");
+assert.sameValue(isNaN(0.000001), false, "0.000001");
+assert.sameValue(isNaN(-0.000001), false, "-0.000001");
+assert.sameValue(isNaN(1e42), false, "1e42");
+assert.sameValue(isNaN(-1e42), false, "-1e42");
+assert.sameValue(isNaN(Infinity), false, "Infinity");
+assert.sameValue(isNaN(-Infinity), false, "-Infinity");
diff --git a/test/built-ins/isNaN/return-true-nan.js b/test/built-ins/isNaN/return-true-nan.js
new file mode 100644
index 0000000000..876c4b5833
--- /dev/null
+++ b/test/built-ins/isNaN/return-true-nan.js
@@ -0,0 +1,19 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Return true if number is NaN
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+  2. If num is NaN, return true.
+includes: [nans.js]
+---*/
+
+distinctNaNs.forEach(function(v, i) {
+  assert.sameValue(isNaN(v), true, "value on position: " + i);
+});
diff --git a/test/built-ins/isNaN/tonumber-operations.js b/test/built-ins/isNaN/tonumber-operations.js
new file mode 100644
index 0000000000..744b8973e0
--- /dev/null
+++ b/test/built-ins/isNaN/tonumber-operations.js
@@ -0,0 +1,28 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  number argument is converted by ToNumber
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+  2. If num is NaN, return true.
+  3. Otherwise, return false.
+---*/
+
+assert.sameValue(isNaN("0"), false, "'0'");
+assert.sameValue(isNaN(""), false, "the empty string");
+assert.sameValue(isNaN("Infinity"), false, "'Infinity'");
+assert.sameValue(isNaN("this is not a number"), true, "string");
+assert.sameValue(isNaN(true), false, "true");
+assert.sameValue(isNaN(false), false, "false");
+assert.sameValue(isNaN([1]), false, "Object [1]");
+assert.sameValue(isNaN([Infinity]), false, "Object [Infinity]");
+assert.sameValue(isNaN([NaN]), true, "Object [NaN]");
+assert.sameValue(isNaN(null), false, "null");
+assert.sameValue(isNaN(undefined), true, "undefined");
+assert.sameValue(isNaN(), true, "no arg");
diff --git a/test/built-ins/isNaN/toprimitive-call-abrupt.js b/test/built-ins/isNaN/toprimitive-call-abrupt.js
new file mode 100644
index 0000000000..31152ee4fd
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-call-abrupt.js
@@ -0,0 +1,30 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Return abrupt completion calling number.@@toPrimitive
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+  5. If exoticToPrim is not undefined, then
+    a. Let result be ? Call(exoticToPrim, input, « hint »).
+features: [Symbol.toPrimitive]
+---*/
+
+var obj = {};
+obj[Symbol.toPrimitive] = function() {
+  throw new Test262Error();
+};
+
+assert.throws(Test262Error, function() {
+  isNaN(obj);
+});
diff --git a/test/built-ins/isNaN/toprimitive-get-abrupt.js b/test/built-ins/isNaN/toprimitive-get-abrupt.js
new file mode 100644
index 0000000000..c3cb940cde
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-get-abrupt.js
@@ -0,0 +1,29 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Return abrupt completion getting number.@@toPrimitive
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+features: [Symbol.toPrimitive]
+---*/
+
+var obj = Object.defineProperty({}, Symbol.toPrimitive, {
+  get: function() {
+    throw new Test262Error();
+  }
+});
+
+assert.throws(Test262Error, function() {
+  isNaN(obj);
+});
diff --git a/test/built-ins/isNaN/toprimitive-not-callable-throws.js b/test/built-ins/isNaN/toprimitive-not-callable-throws.js
new file mode 100644
index 0000000000..dff4ed660c
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-not-callable-throws.js
@@ -0,0 +1,53 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Throws a TypeError if number.@@toPrimitive is not null, undefined, or callable
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+
+  GetMethod (V, P)
+
+  [...]
+  2. Let func be ? GetV(V, P).
+  3. If func is either undefined or null, return undefined.
+  4. If IsCallable(func) is false, throw a TypeError exception.
+features: [Symbol.toPrimitive]
+---*/
+
+var obj = {};
+
+obj[Symbol.toPrimitive] = 42;
+assert.throws(TypeError, function() {
+  isNaN(obj);
+}, "number");
+
+obj[Symbol.toPrimitive] = "";
+assert.throws(TypeError, function() {
+  isNaN(obj);
+}, "string");
+
+obj[Symbol.toPrimitive] = true;
+assert.throws(TypeError, function() {
+  isNaN(obj);
+}, "boolean");
+
+obj[Symbol.toPrimitive] = Symbol.toPrimitive;
+assert.throws(TypeError, function() {
+  isNaN(obj);
+}, "symbol");
+
+obj[Symbol.toPrimitive] = {};
+assert.throws(TypeError, function() {
+  isNaN(obj);
+}, "object");
diff --git a/test/built-ins/isNaN/toprimitive-result-is-object-throws.js b/test/built-ins/isNaN/toprimitive-result-is-object-throws.js
new file mode 100644
index 0000000000..7c0fecc7c3
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-result-is-object-throws.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Throws a TypeError if the result of calling number.@@toPrimitive is an Object
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+  5. If exoticToPrim is not undefined, then
+    a. Let result be ? Call(exoticToPrim, input, « hint »).
+    b. If Type(result) is not Object, return result.
+    c. Throw a TypeError exception.
+features: [Symbol.toPrimitive]
+---*/
+
+var obj = {};
+obj[Symbol.toPrimitive] = function() {
+  return [42];
+};
+
+assert.throws(TypeError, function() {
+  isNaN(obj);
+});
diff --git a/test/built-ins/isNaN/toprimitive-result-is-symbol-throws.js b/test/built-ins/isNaN/toprimitive-result-is-symbol-throws.js
new file mode 100644
index 0000000000..b5320d5022
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-result-is-symbol-throws.js
@@ -0,0 +1,36 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Throws a TypeError if the result of calling number.@@toPrimitive is a symbol
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToNumber ( argument )
+
+  1. Let primValue be ? ToPrimitive(argument, hint Number).
+  2. Return ? ToNumber(primValue).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+  5. If exoticToPrim is not undefined, then
+    a. Let result be ? Call(exoticToPrim, input, « hint »).
+    b. If Type(result) is not Object, return result.
+features: [Symbol.toPrimitive]
+---*/
+
+var obj = {};
+obj[Symbol.toPrimitive] = function() {
+  return Symbol.toPrimitive;
+};
+
+assert.throws(TypeError, function() {
+  isNaN(obj);
+});
diff --git a/test/built-ins/isNaN/toprimitive-valid-result.js b/test/built-ins/isNaN/toprimitive-valid-result.js
new file mode 100644
index 0000000000..b76b271287
--- /dev/null
+++ b/test/built-ins/isNaN/toprimitive-valid-result.js
@@ -0,0 +1,73 @@
+// Copyright (C) 2016 The V8 Project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-isnan-number
+es6id: 18.2.3
+description: >
+  Use non-object value returned from @@toPrimitive method
+info: |
+  isNaN (number)
+
+  1. Let num be ? ToNumber(number).
+
+  ToPrimitive ( input [ , PreferredType ] )
+
+  [...]
+  4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
+  5. If exoticToPrim is not undefined, then
+    a. Let result be ? Call(exoticToPrim, input, « hint »).
+    b. If Type(result) is not Object, return result.
+features: [Symbol.toPrimitive]
+---*/
+
+var called = 0;
+var obj = {
+  valueOf: function() {
+    called = NaN;
+    return Infinity;
+  },
+  toString: function() {
+    called = NaN;
+    return Infinity;
+  }
+};
+
+obj[Symbol.toPrimitive] = function() {
+  called += 1;
+  return 42;
+};
+assert.sameValue(isNaN(obj), false, "use returned value - non-NaN number");
+assert.sameValue(called, 1, "toPrimitive is called - non-NaN number");
+
+called = 0;
+obj[Symbol.toPrimitive] = function() {
+  called += 1;
+  return "this is not a number";
+};
+assert.sameValue(isNaN(obj), true, "use returned value - string to NaN");
+assert.sameValue(called, 1, "toPrimitive is called - string to NaN");
+
+called = 0;
+obj[Symbol.toPrimitive] = function() {
+  called += 1;
+  return true;
+};
+assert.sameValue(isNaN(obj), false, "use returned value - boolean true");
+assert.sameValue(called, 1, "toPrimitive is called - boolean true");
+
+called = 0;
+obj[Symbol.toPrimitive] = function() {
+  called += 1;
+  return false;
+};
+assert.sameValue(isNaN(obj), false, "use returned value - boolean false");
+assert.sameValue(called, 1, "toPrimitive is called - boolean false");
+
+called = 0;
+obj[Symbol.toPrimitive] = function() {
+  called += 1;
+  return NaN;
+};
+assert.sameValue(isNaN(obj), true, "use returned value - NaN");
+assert.sameValue(called, 1, "toPrimitive is called - NaN");