new file mode 100644
--- /dev/null
+++ b/intl/uconv/tests/unit/test_unmapped.js
@@ -0,0 +1,77 @@
+// Tests encoding of unmapped characters
+load('CharsetConversionTests.js');
+
+const inString = "\u2764";
+const expectedString = "?";
+
+function run_test() {
+    var failures = false;
+    var encodingConverter = CreateScriptableConverter();
+
+    // this list excludes codepages that can represent all Unicode
+    var encoders = [
+        "Big5",
+        "Big5-HKSCS",
+        "EUC-JP",
+        "EUC-KR",
+        "gbk",
+        "IBM866",
+        "ISO-2022-JP",
+        "ISO-8859-3",
+        "ISO-8859-4",
+        "ISO-8859-5",
+        "ISO-8859-6",
+        "ISO-8859-7",
+        "ISO-8859-8",
+        "ISO-8859-8-I",
+        "ISO-8859-10",
+        "ISO-8859-13",
+        "ISO-8859-14",
+        "ISO-8859-15",
+        "ISO-8859-16",
+        "ISO-8859-2",
+        "KOI8-R",
+        "KOI8-U",
+        "Shift_JIS",
+        "windows-1250",
+        "windows-1251",
+        "windows-1252",
+        "windows-1253",
+        "windows-1254",
+        "windows-1255",
+        "windows-1256",
+        "windows-1257",
+        "windows-1258",
+        "windows-874",
+        "x-mac-cyrillic"
+    ];
+
+    var counter = 0;
+    while (counter < encoders.length) {
+        var charset = encoders[counter++];
+
+        dump("testing " + counter + " " + charset + "\n");
+        encodingConverter.charset = charset;
+        var codepageString = encodingConverter.ConvertFromUnicode(inString) +
+            encodingConverter.Finish();
+        if (codepageString != expectedString) {
+            dump(charset + " encoding failed\n");
+            for (var i = 0; i < expectedString.length; ++i) {
+                if (i >= codepageString.length) {
+                    dump("output length " + codepageString.length +
+                         " less than expected length " + expectedString.length + "\n");
+                    break;
+                }
+                if (codepageString.charAt(i) != expectedString.charAt(i)) {
+                    dump(i.toString(16) + ": 0x" +
+                         codepageString.charCodeAt(i).toString(16) + " != " +
+                         expectedString.charCodeAt(i).toString(16) + "\n");
+                }
+            }
+            failures = true;
+        }
+    }
+    if (failures) {
+        do_throw("test failed\n");
+    }
+}

--- a/intl/uconv/tests/unit/xpcshell.ini
+++ b/intl/uconv/tests/unit/xpcshell.ini
@@ -115,8 +115,9 @@ support-files =
 [test_encode_x_mac_hebrew.js]
 [test_encode_x_mac_icelandic.js]
 [test_encode_macintosh.js]
 [test_encode_x_mac_romanian.js]
 [test_encode_x_mac_turkish.js]
 [test_utf8_illegals.js]
 [test_input_stream.js]
 [test_bug1008832.js]
+[test_unmapped.js]