Bug 1126509 - Throw if fixIterator() was passed an unknown object. r=jcranmer

mailnews/base/test/unit/test_iteratorUtils.js

@@ -84,6 +84,38 @@ function test_fixIterator() {
     do_check_eq(val, JSArray[i++]);
   }
   do_check_true(i > 0);
+
+  // Bug 1126509, test that fixIterator rejects unknown objects.
+  let thrown = false;
+  let tryIterate = { item: "An object, that is not supported by fixIterator." };
+  try {
+    for (let val in iteratorUtils.fixIterator(tryIterate)) { dump(val); }
+  } catch (e) {
+    // A specific exception is the correct behaviour here.
+    if (e.message == "An unsupported object sent to fixIterator: [object Object]")
+      thrown = true;
+  }
+  do_check_true(thrown);
+
+  thrown = false;
+  try {
+    for (let val of iteratorUtils.fixIterator(tryIterate)) { dump(val); }
+  } catch (e) {
+    // A specific exception is the correct behaviour here.
+    if (e.message == "An unsupported object sent to fixIterator: [object Object]")
+      thrown = true;
+  }
+  do_check_true(thrown);
+
+  thrown = false;
+  try {
+    let result = iteratorUtils.toXPCOMArray(tryIterate, Ci.nsIArray);
+  } catch (e) {
+    // A specific exception is the correct behaviour here.
+    if (e.message == "An unsupported interface requested from toXPCOMArray: nsIArray")
+      thrown = true;
+  }
+  do_check_true(thrown);
 }
 
 /**
@@ -119,6 +151,18 @@ function test_toArray_builtin_iterator() {
     do_check_eq(i, iteratorArray[i][0]);
     do_check_eq(val, iteratorArray[i][1]);
   }
+
+  // Bug 1126509, test that toArray rejects unknown objects.
+  let thrown = false;
+  let tryIterate = { item: "An object, that is not supported by toArray." };
+  try {
+    let result = iteratorUtils.toArray(tryIterate);
+  } catch (e) {
+    // A specific exception is the correct behaviour here.
+    if (e.message == "An unsupported object sent to toArray: [object Object]")
+      thrown = true;
+  }
+  do_check_true(thrown);
 }
 
 const Symbol_iterator = typeof Symbol === "function" && Symbol.iterator ?
@@ -151,6 +195,6 @@ var gTests = [
 ];
 
 function run_test() {
-  for (let [, test] in Iterator(gTests))
+  for (let test of gTests)
     test();
 }

mailnews/base/util/iteratorUtils.jsm

@@ -20,20 +20,20 @@ const ITERATOR_SYMBOL = JS_HAS_SYMBOLS ? Symbol.iterator : "@@iterator";
  * This function will take a number of objects and convert them to an array.
  *
  * Currently, we support the following objects:
- *   NodeList     (i.e. element.childNodes)
  *   Anything you can for (let x of aObj) on
- *                (e.g. toArray(fixIterator(enum))[4])
+ *                (e.g. toArray(fixIterator(enum))[4],
+ *                 also a NodeList from element.childNodes)
  *
  * @param aObj        The object to convert
  */
 function toArray(aObj) {
   if (ITERATOR_SYMBOL in aObj) {
     return Array.from(aObj);
-  } else if (aObj.constructor.contains("NodeList")) {
-    return Array.slice(aObj);
   }
 
-  return null;
+  // We got something unexpected, notify the caller loudly.
+  throw new Error("An unsupported object sent to toArray: " +
+                  (("toString" in aObj) ? aObj.toString() : aObj));
 }
 
 /**
@@ -123,7 +123,9 @@ function fixIterator(aEnum, aIface) {
     })());
   }
 
-  return null;
+  // We got something unexpected, notify the caller loudly.
+  throw new Error("An unsupported object sent to fixIterator: " +
+                  (("toString" in aEnum) ? aEnum.toString() : aEnum));
 }
 
 /**
@@ -148,6 +150,7 @@ function toXPCOMArray(aArray, aInterface) {
     }
     return supportsArray;
   }
+
   if (aInterface.equals(Ci.nsIMutableArray)) {
     let mutableArray = Components.classes["@mozilla.org/array;1"]
                                  .createInstance(Ci.nsIMutableArray);
@@ -157,5 +160,7 @@ function toXPCOMArray(aArray, aInterface) {
     return mutableArray;
   }
 
-  throw "no supports for interface conversion";
+  // We got something unexpected, notify the caller loudly.
+  throw new Error("An unsupported interface requested from toXPCOMArray: " +
+                  aInterface);
 }