diff --git a/test/built-ins/String/prototype/startsWith/coerced-values-of-position.js b/test/built-ins/String/prototype/startsWith/coerced-values-of-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..9a026d0231ed3fa2650bc86c79970f8344d5c511
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/coerced-values-of-position.js
@@ -0,0 +1,39 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns based on coerced values of position.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 9. Let pos be ToInteger(position). (If position is undefined, this step
+ produces the value 0).
+ 10. ReturnIfAbrupt(pos).
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ 16. Otherwise, return false.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert(str.startsWith('The future', NaN), 'NaN coerced to 0');
+assert(str.startsWith('The future', null), 'null coerced to 0');
+assert(str.startsWith('The future', false), 'false coerced to 0');
+assert(str.startsWith('The future', ''), '"" coerced to 0');
+assert(str.startsWith('The future', '0'), '"0" coerced to 0');
+assert(str.startsWith('The future', undefined), 'undefined coerced to 0');
+assert(str.startsWith('The future', 0.4), '0.4 coerced to 0');
+
+assert.sameValue(
+ str.startsWith('The future', true), false,
+ 'true coerced to 1'
+);
+assert.sameValue(str.startsWith('The future', '1'), false, '"1" coerced to 1');
+assert.sameValue(str.startsWith('The future', 1.4), false, '1.4 coerced to 1');
diff --git a/test/built-ins/String/prototype/startsWith/length.js b/test/built-ins/String/prototype/startsWith/length.js
new file mode 100644
index 0000000000000000000000000000000000000000..d3b3f69cc75cb51e389fd6c88758d210eb56f3ed
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/length.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: 21.1.3.18
+description: >
+ String.prototype.startsWith.length value and descriptor.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ The length property of the startsWith method is 1.
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+ String.prototype.startsWith.length, 1,
+ 'The value of `String.prototype.startsWith.length` is `1`'
+);
+
+verifyNotEnumerable(String.prototype.startsWith, 'length');
+verifyNotWritable(String.prototype.startsWith, 'length');
+verifyConfigurable(String.prototype.startsWith, 'length');
diff --git a/test/built-ins/String/prototype/startsWith/name.js b/test/built-ins/String/prototype/startsWith/name.js
new file mode 100644
index 0000000000000000000000000000000000000000..1a8b94ecbb7b5f8e030353cc1342df0d9d925f9e
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/name.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: 21.1.3.18
+description: >
+ String.prototype.startsWith.name value and descriptor.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 17 ECMAScript Standard Built-in Objects
+
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+ String.prototype.startsWith.name, 'startsWith',
+ 'The value of `String.prototype.startsWith.name` is `"startsWith"`'
+);
+
+verifyNotEnumerable(String.prototype.startsWith, 'name');
+verifyNotWritable(String.prototype.startsWith, 'name');
+verifyConfigurable(String.prototype.startsWith, 'name');
diff --git a/test/built-ins/String/prototype/startsWith/out-of-bounds-position.js b/test/built-ins/String/prototype/startsWith/out-of-bounds-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..b71def3824bd2b84c65c6362697e8c9ce0bb11e4
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/out-of-bounds-position.js
@@ -0,0 +1,43 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns false if searchLength + start position is greater than string length.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert.sameValue(
+ str.startsWith('!', str.length), false,
+ 'str.startsWith("!", str.length) returns false'
+);
+
+assert.sameValue(
+ str.startsWith('!', 100), false,
+ 'str.startsWith("!", 100) returns false'
+);
+
+assert.sameValue(
+ str.startsWith('!', Infinity), false,
+ 'str.startsWith("!", Infinity) returns false'
+);
+
+assert(
+ str.startsWith('The future', -1),
+ 'position argument < 0 will search from the start of the string (-1)'
+);
+
+assert(
+ str.startsWith('The future', -Infinity),
+ 'position argument < 0 will search from the start of the string (-Infinity)'
+);
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-position-as-symbol.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-position-as-symbol.js
new file mode 100644
index 0000000000000000000000000000000000000000..3137735407405c1b16ba16756d41905399fdd03e
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-position-as-symbol.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: 21.1.3.18
+description: >
+ Returns abrupt from ToInteger(position) as a Symbol.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 9. Let pos be ToInteger(position). (If position is undefined, this step
+ produces the value 0).
+ 10. ReturnIfAbrupt(pos).
+ ...
+features: [Symbol]
+---*/
+
+var position = Symbol();
+
+assert.throws(TypeError, function() {
+ ''.startsWith('', position);
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-position.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..0976dc6d8229013c37ba84d3480678b0e9b779d8
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-position.js
@@ -0,0 +1,25 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns abrupt from ToInteger(position).
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 9. Let pos be ToInteger(position). (If position is undefined, this step
+ produces the value 0).
+ 10. ReturnIfAbrupt(pos).
+ ...
+---*/
+
+var position = {
+ valueOf: function() {
+ throw new Test262Error();
+ }
+};
+
+assert.throws(Test262Error, function() {
+ ''.startsWith('', position);
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-as-symbol.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-as-symbol.js
new file mode 100644
index 0000000000000000000000000000000000000000..a4c590fae78539d7cd8d711fdef7c61cc805240c
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-as-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: 21.1.3.18
+description: >
+ Returns abrupt from ToString(searchString) as a Symbol
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 7. Let searchStr be ToString(searchString).
+ 8. ReturnIfAbrupt(searchString).
+ ...
+features: [Symbol]
+---*/
+
+var s = Symbol();
+
+assert.throws(TypeError, function() {
+ ''.startsWith(s);
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-regexp-test.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-regexp-test.js
new file mode 100644
index 0000000000000000000000000000000000000000..e31ca6886566199a929819888d4c218cb23f9f7a
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring-regexp-test.js
@@ -0,0 +1,42 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns abrupt from IsRegExp(searchString).
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 4. Let isRegExp be IsRegExp(searchString).
+ 5. ReturnIfAbrupt(isRegExp).
+ ...
+
+ 7.2.8 IsRegExp ( argument )
+
+ 2. Let isRegExp be Get(argument, @@match).
+ 3. ReturnIfAbrupt(isRegExp).
+features: [Symbol.match]
+---*/
+
+var obj = {};
+Object.defineProperty(obj, Symbol.match, {
+ get: function() {
+ throw new Test262Error();
+ }
+});
+
+assert.throws(Test262Error, function() {
+ ''.startsWith(obj);
+});
+
+var regexp = /./;
+Object.defineProperty(regexp, Symbol.match, {
+ get: function() {
+ throw new Test262Error();
+ }
+});
+
+assert.throws(Test262Error, function() {
+ ''.startsWith(regexp);
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring.js
new file mode 100644
index 0000000000000000000000000000000000000000..8226fdbc37cd05bb567fd4c167b61a234d35145f
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-searchstring.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: 21.1.3.18
+description: >
+ Returns abrupt from ToString(searchString)
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 7. Let searchStr be ToString(searchString).
+ 8. ReturnIfAbrupt(searchString).
+ ...
+---*/
+
+var obj = {
+ toString: function() {
+ throw new Test262Error();
+ }
+};
+
+assert.throws(Test262Error, function() {
+ ''.startsWith(obj);
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-this-as-symbol.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-this-as-symbol.js
new file mode 100644
index 0000000000000000000000000000000000000000..e712e4c7af2c5152f26230e45af06bb2345ca276
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-this-as-symbol.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: 21.1.3.18
+description: >
+ Returns abrupt from ToString(this) where this is a Symbol
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 1. Let O be RequireObjectCoercible(this value).
+ 2. Let S be ToString(O).
+ 3. ReturnIfAbrupt(S).
+features: [Symbol]
+---*/
+
+var s = Symbol('');
+
+assert.throws(TypeError, function() {
+ String.prototype.startsWith.call(s, '');
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-abrupt-from-this.js b/test/built-ins/String/prototype/startsWith/return-abrupt-from-this.js
new file mode 100644
index 0000000000000000000000000000000000000000..294c7c70ab10704d0f4bd7973132817d7c85861f
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-abrupt-from-this.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: 21.1.3.18
+description: >
+ Returns abrupt from ToString(this)
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 1. Let O be RequireObjectCoercible(this value).
+ 2. Let S be ToString(O).
+ 3. ReturnIfAbrupt(S).
+---*/
+
+var o = {
+ toString: function() {
+ throw new Test262Error();
+ }
+};
+
+assert.throws(Test262Error, function() {
+ String.prototype.startsWith.call(o, '');
+});
diff --git a/test/built-ins/String/prototype/startsWith/return-true-if-searchstring-is-empty.js b/test/built-ins/String/prototype/startsWith/return-true-if-searchstring-is-empty.js
new file mode 100644
index 0000000000000000000000000000000000000000..d9e819747ebe8b59de6245df2dac5e4c05e9e209
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/return-true-if-searchstring-is-empty.js
@@ -0,0 +1,40 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns true if searchString.length == 0.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert(
+ str.startsWith(''),
+ 'str.startsWith("") returns true'
+);
+
+assert(
+ str.startsWith('', str.length),
+ 'str.startsWith("", str.length) returns true'
+);
+
+assert(
+ str.startsWith(''),
+ 'str.startsWith("") returns true'
+);
+
+assert(
+ str.startsWith('', Infinity),
+ 'str.startsWith("", Infinity) returns true'
+);
\ No newline at end of file
diff --git a/test/built-ins/String/prototype/startsWith/searchstring-found-with-position.js b/test/built-ins/String/prototype/startsWith/searchstring-found-with-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..a9b60e00d80638c9e9a1b4ff0db8a518abcdc8e5
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/searchstring-found-with-position.js
@@ -0,0 +1,34 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns true if searchString appears as a substring of the given string with a
+ given position.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert(
+ str.startsWith('The future', 0),
+ 'str.startsWith("The future", 0) === true'
+);
+assert(
+ str.startsWith('future', 4),
+ 'str.startsWith("future", 4) === true'
+);
+assert(
+ str.startsWith(' is cool!', 10),
+ 'str.startsWith(" is cool!", 10) === true'
+);
diff --git a/test/built-ins/String/prototype/startsWith/searchstring-found-without-position.js b/test/built-ins/String/prototype/startsWith/searchstring-found-without-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..5fe3bfcbf52a67f03ec99b3fa1fae2d3c219116d
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/searchstring-found-without-position.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: 21.1.3.18
+description: >
+ Returns true if searchString appears as a substring of the given string.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert(str.startsWith('The '), 'str.startsWith("The ") === true');
+assert(str.startsWith('The future'), 'str.startsWith("The future") === true');
+assert(str.startsWith(str), 'str.startsWith(str) === true');
diff --git a/test/built-ins/String/prototype/startsWith/searchstring-is-regexp-throws.js b/test/built-ins/String/prototype/startsWith/searchstring-is-regexp-throws.js
new file mode 100644
index 0000000000000000000000000000000000000000..b7749e53aa72a3f0d779c54213309dadf98c565d
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/searchstring-is-regexp-throws.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: 21.1.3.18
+description: >
+ Throws a TypeError if searchString is a RegExp.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 4. Let isRegExp be IsRegExp(searchString).
+ 5. ReturnIfAbrupt(isRegExp).
+ 6. If isRegExp is true, throw a TypeError exception.
+ ...
+---*/
+
+var searchString = /./;
+
+assert.throws(TypeError, function() {
+ ''.startsWith(searchString);
+});
diff --git a/test/built-ins/String/prototype/startsWith/searchstring-not-found-with-position.js b/test/built-ins/String/prototype/startsWith/searchstring-not-found-with-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..14117c8fb8a027c1db246661009b59a4b8ec10d1
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/searchstring-not-found-with-position.js
@@ -0,0 +1,31 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns false if searchString is not found with a given position.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ 16. Otherwise, return false.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert.sameValue(
+ str.startsWith('The future', 1), false,
+ 'str.startsWith("The future", 1) === false'
+);
+
+assert.sameValue(
+ str.startsWith(str, 1), false,
+ 'str.startsWith(str, 1) === false'
+);
diff --git a/test/built-ins/String/prototype/startsWith/searchstring-not-found-without-position.js b/test/built-ins/String/prototype/startsWith/searchstring-not-found-without-position.js
new file mode 100644
index 0000000000000000000000000000000000000000..80a7a14e246561d93211f51d07e4720440113348
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/searchstring-not-found-without-position.js
@@ -0,0 +1,34 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Returns false if searchString is not found.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ ...
+ 11. Let len be the number of elements in S.
+ 12. Let start be min(max(pos, 0), len).
+ 13. Let searchLength be the number of elements in searchStr.
+ 14. If searchLength+start is greater than len, return false.
+ 15. If the sequence of elements of S starting at start of length searchLength
+ is the same as the full element sequence of searchStr, return true.
+ 16. Otherwise, return false.
+ ...
+---*/
+
+var str = 'The future is cool!';
+
+assert.sameValue(
+ str.startsWith('Flash'), false,
+ 'str.startsWith("Flash") === false'
+);
+assert.sameValue(
+ str.startsWith('THE FUTURE'), false,
+ 'startsWith is case sensitive'
+);
+assert.sameValue(
+ str.startsWith('future is cool!'), false,
+ 'str.startsWith("future is cool!") === false'
+);
diff --git a/test/built-ins/String/prototype/startsWith/startsWith.js b/test/built-ins/String/prototype/startsWith/startsWith.js
new file mode 100644
index 0000000000000000000000000000000000000000..54c063095ba8172c29722177558a0873eed55e37
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/startsWith.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: 21.1.3.18
+description: >
+ Property type and descriptor.
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 17 ECMAScript Standard Built-in Objects
+includes: [propertyHelper.js]
+---*/
+
+assert.sameValue(
+ typeof String.prototype.startsWith,
+ 'function',
+ '`typeof String.prototype.startsWith` is `function`'
+);
+
+verifyNotEnumerable(String.prototype, 'startsWith');
+verifyWritable(String.prototype, 'startsWith');
+verifyConfigurable(String.prototype, 'startsWith');
diff --git a/test/built-ins/String/prototype/startsWith/this-is-null-throws.js b/test/built-ins/String/prototype/startsWith/this-is-null-throws.js
new file mode 100644
index 0000000000000000000000000000000000000000..d89d0abd2023b564f2a8a6b3ad56e76eb45438de
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/this-is-null-throws.js
@@ -0,0 +1,16 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Throws TypeError when `this` is null
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 1. Let O be RequireObjectCoercible(this value).
+ 2. Let S be ToString(O).
+---*/
+
+assert.throws(TypeError, function() {
+ String.prototype.startsWith.call(null, '');
+});
diff --git a/test/built-ins/String/prototype/startsWith/this-is-undefined-throws.js b/test/built-ins/String/prototype/startsWith/this-is-undefined-throws.js
new file mode 100644
index 0000000000000000000000000000000000000000..bf54727cd0bdd1abba6e4fd4b81088b64cd1523e
--- /dev/null
+++ b/test/built-ins/String/prototype/startsWith/this-is-undefined-throws.js
@@ -0,0 +1,16 @@
+// Copyright (C) 2015 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+es6id: 21.1.3.18
+description: >
+ Throws TypeError when `this` is undefined
+info: >
+ 21.1.3.18 String.prototype.startsWith ( searchString [ , position ] )
+
+ 1. Let O be RequireObjectCoercible(this value).
+ 2. Let S be ToString(O).
+---*/
+
+assert.throws(TypeError, function() {
+ String.prototype.startsWith.call(undefined, '');
+});