From 8abebec458ff72c2e940c5055fa9497068b68744 Mon Sep 17 00:00:00 2001
From: Ms2ger <ms2ger@gmail.com>
Date: Thu, 29 Mar 2012 23:09:09 +0200
Subject: [PATCH] Bug 738647 - DOMStorageImpl::GetKey shouldn't throw; r=honzab

---
 dom/interfaces/storage/nsIDOMStorage.idl      |  3 +-
 dom/src/storage/nsDOMStorage.cpp              |  9 ++--
 .../localstorage/test_localStorageBase.html   | 45 +++++++------------
 .../test_localStorageBasePrivateBrowsing.html | 45 +++++++------------
 .../test_localStorageBaseSessionOnly.html     | 45 +++++++------------
 .../test_sessionStorageBase.html              | 45 +++++++------------
 6 files changed, 64 insertions(+), 128 deletions(-)

diff --git a/dom/interfaces/storage/nsIDOMStorage.idl b/dom/interfaces/storage/nsIDOMStorage.idl
index b09ebc3cff6..e393da6b783 100644
--- a/dom/interfaces/storage/nsIDOMStorage.idl
+++ b/dom/interfaces/storage/nsIDOMStorage.idl
@@ -64,8 +64,7 @@ interface nsIDOMStorage : nsISupports
    * Retrieve the name of the key at a particular index.
    *
    * @param index index of the item to retrieve
-   * @returns the key at index
-   * @throws INDEX_SIZE_ERR if there is no key at that index
+   * @returns the key at index, null if there is no key at that index
    */
   DOMString key(in unsigned long index);
 
diff --git a/dom/src/storage/nsDOMStorage.cpp b/dom/src/storage/nsDOMStorage.cpp
index a116ca20865..116752d6ca1 100644
--- a/dom/src/storage/nsDOMStorage.cpp
+++ b/dom/src/storage/nsDOMStorage.cpp
@@ -1131,10 +1131,6 @@ IndexFinder(nsSessionStorageEntry* aEntry, void* userArg)
 nsresult
 DOMStorageImpl::GetKey(bool aCallerSecure, PRUint32 aIndex, nsAString& aKey)
 {
-  // XXXjst: This is as retarded as the DOM spec is, takes an unsigned
-  // int, but the spec talks about what to do if a negative value is
-  // passed in.
-
   // XXX: This does a linear search for the key at index, which would
   // suck if there's a large numer of indexes. Do we care? If so,
   // maybe we need to have a lazily populated key array here or
@@ -1148,8 +1144,9 @@ DOMStorageImpl::GetKey(bool aCallerSecure, PRUint32 aIndex, nsAString& aKey)
   mItems.EnumerateEntries(IndexFinder, &data);
 
   if (!data.mItem) {
-    // aIndex was larger than the number of accessible keys. Throw.
-    return NS_ERROR_DOM_INDEX_SIZE_ERR;
+    // aIndex was larger than the number of accessible keys. Return null.
+    aKey.SetIsVoid(true);
+    return NS_OK;
   }
 
   aKey = data.mItem->GetKey();
diff --git a/dom/tests/mochitest/localstorage/test_localStorageBase.html b/dom/tests/mochitest/localstorage/test_localStorageBase.html
index 630702755f7..11d86c79e5b 100644
--- a/dom/tests/mochitest/localstorage/test_localStorageBase.html
+++ b/dom/tests/mochitest/localstorage/test_localStorageBase.html
@@ -7,28 +7,13 @@
 
 <script type="text/javascript">
 
-var INDEX_SIZE_ERR = 1;
-
-function checkException(func, exc)
-{
-  var exceptionThrew = false;
-  try {
-    func();
-  }
-  catch (ex) {
-    exceptionThrew = true;
-    is(ex.code, exc, "Expected "+exc+" exception");
-  }
-  ok(exceptionThrew, "Exception "+exc+" threw");
-}
-
 function startTest()
 {
   // Initially check the localStorage is empty
   is(localStorage.length, 0, "The storage is empty [1]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null (getItem())");
   is(localStorage["nonexisting"], null, "Nonexisting item is null (array access)");
   is(localStorage.nonexisting, null, "Nonexisting item is null (property access)");
@@ -62,8 +47,8 @@ function startTest()
   localStorage.setItem("key1", "value1");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
 
   // check all access method give the correct result
   // and are of the correct type
@@ -78,7 +63,7 @@ function startTest()
   // remove the previously added key and check the storage is empty
   localStorage.removeItem("key1");
   is(localStorage.length, 0, "The storage is empty [2]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), null, "\'key1\' removed");
 
   is(typeof localStorage.getItem("key1"), "object", "getItem('key1') is object");
@@ -107,8 +92,8 @@ function startTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -117,8 +102,8 @@ function startTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -126,8 +111,8 @@ function startTest()
   localStorage.removeItem("key2");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
   
   // JS property test
@@ -166,9 +151,9 @@ function startTest()
   is("testB" in localStorage, false, "Keys are not in the JS scope of the storage");
   is("testC" in localStorage, false, "Keys are not in the JS scope of the storage");
   is(localStorage.length, 0, "The storage is empty [3]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR); // this is unspecified!
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null");
   is(localStorage.getItem("key1"), null, "key1 removed");
   is(localStorage.getItem("key2"), null, "key2 removed");
diff --git a/dom/tests/mochitest/localstorage/test_localStorageBasePrivateBrowsing.html b/dom/tests/mochitest/localstorage/test_localStorageBasePrivateBrowsing.html
index da96897abaa..f393a4fd3e9 100644
--- a/dom/tests/mochitest/localstorage/test_localStorageBasePrivateBrowsing.html
+++ b/dom/tests/mochitest/localstorage/test_localStorageBasePrivateBrowsing.html
@@ -8,21 +8,6 @@
 
 <script type="text/javascript">
 
-var INDEX_SIZE_ERR = 1;
-
-function checkException(func, exc)
-{
-  var exceptionThrew = false;
-  try {
-    func();
-  }
-  catch (ex) {
-    exceptionThrew = true;
-    is(ex.code, exc, "Expected "+exc+" exception");
-  }
-  ok(exceptionThrew, "Exception "+exc+" threw");
-}
-
 function startTest()
 {
   netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
@@ -45,9 +30,9 @@ function doTest()
 
   // Initially check the localStorage is empty
   is(localStorage.length, 0, "The storage is empty [1]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null (getItem())");
   is(localStorage["nonexisting"], null, "Nonexisting item is null (array access)");
   is(localStorage.nonexisting, null, "Nonexisting item is null (property access)");
@@ -81,8 +66,8 @@ function doTest()
   localStorage.setItem("key1", "value1");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
 
   // check all access method give the correct result
   // and are of the correct type
@@ -97,7 +82,7 @@ function doTest()
   // remove the previously added key and check the storage is empty
   localStorage.removeItem("key1");
   is(localStorage.length, 0, "The storage is empty [2]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), null, "\'key1\' removed");
 
   is(typeof localStorage.getItem("key1"), "object", "getItem('key1') is object");
@@ -126,8 +111,8 @@ function doTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -136,8 +121,8 @@ function doTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -145,8 +130,8 @@ function doTest()
   localStorage.removeItem("key2");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
 
   // JS property test
@@ -183,9 +168,9 @@ function doTest()
   // Clear the storage
   localStorage.clear();
   is(localStorage.length, 0, "The storage is empty [3]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR); // this is unspecified!
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null");
   is(localStorage.getItem("key1"), null, "key1 removed");
   is(localStorage.getItem("key2"), null, "key2 removed");
diff --git a/dom/tests/mochitest/localstorage/test_localStorageBaseSessionOnly.html b/dom/tests/mochitest/localstorage/test_localStorageBaseSessionOnly.html
index e913d434e22..5cb78e152b6 100644
--- a/dom/tests/mochitest/localstorage/test_localStorageBaseSessionOnly.html
+++ b/dom/tests/mochitest/localstorage/test_localStorageBaseSessionOnly.html
@@ -7,21 +7,6 @@
 
 <script type="text/javascript">
 
-var INDEX_SIZE_ERR = 1;
-
-function checkException(func, exc)
-{
-  var exceptionThrew = false;
-  try {
-    func();
-  }
-  catch (ex) {
-    exceptionThrew = true;
-    is(ex.code, exc, "Expected "+exc+" exception");
-  }
-  ok(exceptionThrew, "Exception "+exc+" threw");
-}
-
 function startTest()
 {
   netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
@@ -36,9 +21,9 @@ function startTest()
 
   // Initially check the localStorage is empty
   is(localStorage.length, 0, "The storage is empty [1]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null (getItem())");
   is(localStorage["nonexisting"], null, "Nonexisting item is null (array access)");
   is(localStorage.nonexisting, null, "Nonexisting item is null (property access)");
@@ -72,8 +57,8 @@ function startTest()
   localStorage.setItem("key1", "value1");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
 
   // check all access method give the correct result
   // and are of the correct type
@@ -88,7 +73,7 @@ function startTest()
   // remove the previously added key and check the storage is empty
   localStorage.removeItem("key1");
   is(localStorage.length, 0, "The storage is empty [2]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), null, "\'key1\' removed");
 
   is(typeof localStorage.getItem("key1"), "object", "getItem('key1') is object");
@@ -117,8 +102,8 @@ function startTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -127,8 +112,8 @@ function startTest()
   is(localStorage.length, 2, "The storage has two key-value pairs");
   is(localStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(localStorage.key(1), secondKey);
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(2);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
   is(localStorage.getItem("key2"), "value2-2");
 
@@ -136,8 +121,8 @@ function startTest()
   localStorage.removeItem("key2");
   is(localStorage.length, 1, "The storage has one key-value pair");
   is(localStorage.key(0), "key1");
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("key1"), "value1-2");
 
   // JS property test
@@ -174,9 +159,9 @@ function startTest()
   // Clear the storage
   localStorage.clear();
   is(localStorage.length, 0, "The storage is empty [3]");
-  checkException(function() {localStorage.key(0);}, INDEX_SIZE_ERR); // this is unspecified!
-  checkException(function() {localStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {localStorage.key(1);}, INDEX_SIZE_ERR);
+  is(localStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(localStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(localStorage.getItem("nonexisting"), null, "Nonexisting item is null");
   is(localStorage.getItem("key1"), null, "key1 removed");
   is(localStorage.getItem("key2"), null, "key2 removed");
diff --git a/dom/tests/mochitest/sessionstorage/test_sessionStorageBase.html b/dom/tests/mochitest/sessionstorage/test_sessionStorageBase.html
index ef57100f2de..3ec1bbc251b 100644
--- a/dom/tests/mochitest/sessionstorage/test_sessionStorageBase.html
+++ b/dom/tests/mochitest/sessionstorage/test_sessionStorageBase.html
@@ -7,30 +7,15 @@
 
 <script type="text/javascript">
 
-var INDEX_SIZE_ERR = 1;
-
-function checkException(func, exc)
-{
-  var exceptionThrew = false;
-  try {
-    func();
-  }
-  catch (ex) {
-    exceptionThrew = true;
-    is(ex.code, exc, "Expected "+exc+" exception");
-  }
-  ok(exceptionThrew, "Exception "+exc+" threw");
-}
-
 function startTest()
 {
   sessionStorage.clear();
   
   // Initially check the sessionStorage is empty
   is(sessionStorage.length, 0, "The storage is empty [1]");
-  checkException(function() {sessionStorage.key(0);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(1);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("nonexisting"), null, "Nonexisting item is null (getItem())");
   is(sessionStorage["nonexisting"], null, "Nonexisting item is null (array access)");
   is(sessionStorage.nonexisting, null, "Nonexisting item is null (property access)");
@@ -64,8 +49,8 @@ function startTest()
   sessionStorage.setItem("key1", "value1");
   is(sessionStorage.length, 1, "The storage has one key-value pair");
   is(sessionStorage.key(0), "key1");
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(1);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(1), null, "key() should return null for out-of-bounds access");
 
   // check all access method give the correct result
   // and are of the correct type
@@ -80,7 +65,7 @@ function startTest()
   // remove the previously added key and check the storage is empty
   sessionStorage.removeItem("key1");
   is(sessionStorage.length, 0, "The storage is empty [2]");
-  checkException(function() {sessionStorage.key(0);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(0), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("key1"), null, "\'key1\' removed");
 
   is(typeof sessionStorage.getItem("key1"), "object", "getItem('key1') is object");
@@ -109,8 +94,8 @@ function startTest()
   is(sessionStorage.length, 2, "The storage has two key-value pairs");
   is(sessionStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(sessionStorage.key(1), secondKey);
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(2);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("key1"), "value1");
   is(sessionStorage.getItem("key2"), "value2-2");
 
@@ -119,8 +104,8 @@ function startTest()
   is(sessionStorage.length, 2, "The storage has two key-value pairs");
   is(sessionStorage.key(0), firstKey); // After key value changes the order must be preserved
   is(sessionStorage.key(1), secondKey);
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(2);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(2), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("key1"), "value1-2");
   is(sessionStorage.getItem("key2"), "value2-2");
 
@@ -128,16 +113,16 @@ function startTest()
   sessionStorage.removeItem("key2");
   is(sessionStorage.length, 1, "The storage has one key-value pair");
   is(sessionStorage.key(0), "key1");
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(1);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("key1"), "value1-2");
 
   // Clear the storage
   sessionStorage.clear();
   is(sessionStorage.length, 0, "The storage is empty [3]");
-  checkException(function() {sessionStorage.key(0);}, INDEX_SIZE_ERR); // this is unspecified!
-  checkException(function() {sessionStorage.key(-1);}, INDEX_SIZE_ERR);
-  checkException(function() {sessionStorage.key(1);}, INDEX_SIZE_ERR);
+  is(sessionStorage.key(0), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(-1), null, "key() should return null for out-of-bounds access");
+  is(sessionStorage.key(1), null, "key() should return null for out-of-bounds access");
   is(sessionStorage.getItem("nonexisting"), null, "Nonexisting item is null");
   is(sessionStorage.getItem("key1"), null, "key1 removed");
   is(sessionStorage.getItem("key2"), null, "key2 removed");