diff -r 000000000000 -r 6474c204b198 toolkit/components/url-classifier/tests/unit/test_backoff.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/url-classifier/tests/unit/test_backoff.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,89 @@
+// Some unittests (e.g., paste into JS shell)
+var jslib = Cc["@mozilla.org/url-classifier/jslib;1"].
+            getService().wrappedJSObject;
+var _Datenow = jslib.Date.now;
+function setNow(time) {
+  jslib.Date.now = function() {
+    return time;
+  }
+}
+
+function run_test() {
+  // 3 errors, 1ms retry period, max 3 requests per ten milliseconds,
+  // 5ms backoff interval, 19ms max delay
+  var rb = new jslib.RequestBackoff(3, 1, 3, 10, 5, 19);
+  setNow(1);
+  rb.noteServerResponse(200);
+  do_check_true(rb.canMakeRequest());
+  setNow(2);
+  do_check_true(rb.canMakeRequest());
+
+  // First error should trigger a 1ms delay
+  rb.noteServerResponse(500);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 3);
+  setNow(3);
+  do_check_true(rb.canMakeRequest());
+
+  // Second error should also trigger a 1ms delay
+  rb.noteServerResponse(500);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 4);
+  setNow(4);
+  do_check_true(rb.canMakeRequest());
+
+  // Third error should trigger a 5ms backoff
+  rb.noteServerResponse(500);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 9);
+  setNow(9);
+  do_check_true(rb.canMakeRequest());
+
+  // Trigger backoff again
+  rb.noteServerResponse(503);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 19);
+  setNow(19);
+  do_check_true(rb.canMakeRequest());
+
+  // Trigger backoff a third time and hit max timeout
+  rb.noteServerResponse(302);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 38);
+  setNow(38);
+  do_check_true(rb.canMakeRequest());
+
+  // One more backoff, should still be at the max timeout
+  rb.noteServerResponse(400);
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 57);
+  setNow(57);
+  do_check_true(rb.canMakeRequest());
+
+  // Request goes through
+  rb.noteServerResponse(200);
+  do_check_true(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 0);
+  setNow(58);
+  rb.noteServerResponse(500);
+
+  // Another error, should trigger a 1ms backoff
+  do_check_false(rb.canMakeRequest());
+  do_check_eq(rb.nextRequestTime_, 59);
+
+  setNow(59);
+  do_check_true(rb.canMakeRequest());
+
+  setNow(200);
+  rb.noteRequest();
+  setNow(201);
+  rb.noteRequest();
+  setNow(202);
+  do_check_true(rb.canMakeRequest());
+  rb.noteRequest();
+  do_check_false(rb.canMakeRequest());
+  setNow(211);
+  do_check_true(rb.canMakeRequest());
+
+  jslib.Date.now = _Datenow;
+}