new file mode 100644
--- /dev/null
+++ b/intl/uconv/tests/unit/test_input_stream.js
@@ -0,0 +1,33 @@
+var Ci = Components.interfaces,
+    Cc = Components.classes,
+    CC = Components.Constructor;
+var converter = Cc["@mozilla.org/intl/scriptableunicodeconverter"]
+                  .createInstance(Ci.nsIScriptableUnicodeConverter);
+converter.charset = "UTF-8";
+
+var SIS = CC("@mozilla.org/scriptableinputstream;1",
+             "nsIScriptableInputStream",
+             "init");
+
+function test_char(code) {
+    dump("test_char(0x" + code.toString(16) + ")\n");
+    var original = String.fromCharCode(code);
+    var nativeStream = converter.convertToInputStream(original);
+    var stream = new SIS(nativeStream);
+    var utf8Result = stream.read(stream.available());
+    stream.close();
+    var result = converter.ConvertToUnicode(utf8Result);
+    do_check_eq(escape(original), escape(result));
+}
+
+function run_test() {
+    // This is not a very comprehensive test.
+    for (var i = 0x007f - 2; i <= 0x007f; i++)
+        test_char(i);
+    for (i = 0x07ff - 2; i <= 0x07ff; i++)
+        test_char(i);
+    for (i = 0x1000 - 2; i <= 0x1000 + 2; i++)
+        test_char(i);
+    for (i = 0xe000; i <= 0xe000 + 2; i++)
+        test_char(i);
+}

--- a/intl/uconv/tests/unit/xpcshell.ini
+++ b/intl/uconv/tests/unit/xpcshell.ini
@@ -150,8 +150,9 @@ support-files =
 [test_encode_x_mac_hebrew_internal.js]
 [test_encode_x_mac_icelandic.js]
 [test_encode_macintosh.js]
 [test_encode_x_mac_romanian.js]
 [test_encode_x_mac_turkish.js]
 [test_encode_x_mac_ukrainian.js]
 [test_iso2022KR.js]
 [test_utf8_illegals.js]
+[test_input_stream.js]