diff --git a/services/sync/tests/unit/head_first.js b/services/sync/tests/unit/head_first.js
index ac1d1543c1d3..7af151bfd8f4 100644
--- a/services/sync/tests/unit/head_first.js
+++ b/services/sync/tests/unit/head_first.js
@@ -3,6 +3,7 @@ version(180);
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 const Cr = Components.results;
+const Cu = Components.utils;
 
 let ds = Cc["@mozilla.org/file/directory_service;1"]
   .getService(Ci.nsIProperties);
@@ -40,37 +41,69 @@ function loadInSandbox(aUri) {
   return sandbox;
 }
 
-function makeAsyncTestRunner(generator) {
-  const Cu = Components.utils;
+function FakeTimerService() {
+  Cu.import("resource://weave/util.js");
 
+  this.callbackQueue = [];
+
+  var self = this;
+
+  this.__proto__ = {
+    makeTimerForCall: function FTS_makeTimerForCall(cb) {
+      // Just add the callback to our queue and we'll call it later, so
+      // as to simulate a real nsITimer.
+      self.callbackQueue.push(cb);
+      return "fake nsITimer";
+    },
+    processCallback: function FTS_processCallbacks() {
+      var cb = self.callbackQueue.pop();
+      if (cb) {
+        cb();
+        return true;
+      }
+      return false;
+    }
+  };
+
+  Utils.makeTimerForCall = self.makeTimerForCall;
+};
+
+function initTestLogging() {
   Cu.import("resource://weave/log4moz.js");
-  Cu.import("resource://weave/async.js");
 
-  var errorsLogged = 0;
-
-  function _TestFormatter() {}
-  _TestFormatter.prototype = {
+  function LogStats() {
+    this.errorsLogged = 0;
+  }
+  LogStats.prototype = {
     format: function BF_format(message) {
       if (message.level == Log4Moz.Level.Error)
-        errorsLogged += 1;
+        this.errorsLogged += 1;
       return message.loggerName + "\t" + message.levelDesc + "\t" +
         message.message + "\n";
     }
   };
-  _TestFormatter.prototype.__proto__ = new Log4Moz.Formatter();
+  LogStats.prototype.__proto__ = new Log4Moz.Formatter();
 
   var log = Log4Moz.Service.rootLogger;
-  var formatter = new _TestFormatter();
-  var appender = new Log4Moz.DumpAppender(formatter);
+  var logStats = new LogStats();
+  var appender = new Log4Moz.DumpAppender(logStats);
   log.level = Log4Moz.Level.Debug;
   appender.level = Log4Moz.Level.Debug;
   log.addAppender(appender);
 
+  return logStats;
+}
+
+function makeAsyncTestRunner(generator) {
+  Cu.import("resource://weave/async.js");
+
+  var logStats = initTestLogging();
+
   function run_test() {
     do_test_pending();
 
     let onComplete = function() {
-      if (errorsLogged)
+      if (logStats.errorsLogged)
         do_throw("Errors were logged.");
       else
         do_test_finished();
diff --git a/services/sync/tests/unit/test_async.js b/services/sync/tests/unit/test_async.js
index 36795e9948a4..746033ac4754 100644
--- a/services/sync/tests/unit/test_async.js
+++ b/services/sync/tests/unit/test_async.js
@@ -1,20 +1,11 @@
-const Cu = Components.utils;
-
 Cu.import("resource://weave/util.js");
 Cu.import("resource://weave/async.js");
 
 function run_test() {
-  var callbackQueue = [];
+  var fts = new FakeTimerService();
 
   Function.prototype.async = Async.sugar;
 
-  Utils.makeTimerForCall = function fake_makeTimerForCall(cb) {
-    // Just add the callback to our queue and we'll call it later, so
-    // as to simulate a real nsITimer.
-    callbackQueue.push(cb);
-    return "fake nsITimer";
-  };
-
   var onCompleteCalled = false;
 
   function onComplete() {
@@ -33,9 +24,7 @@ function run_test() {
     // Ensure that 'this' is set properly.
     do_check_eq(this.sampleProperty, true);
 
-    // Simulate the calling of an asynchronous function that will call
-    // our callback.
-    callbackQueue.push(self.cb);
+    fts.makeTimerForCall(self.cb);
     yield;
 
     timesYielded++;
@@ -47,15 +36,11 @@ function run_test() {
 
   do_check_eq(timesYielded, 1);
 
-  let func = callbackQueue.pop();
-  do_check_eq(typeof func, "function");
-  func();
+  do_check_true(fts.processCallback());
 
   do_check_eq(timesYielded, 2);
 
-  func = callbackQueue.pop();
-  do_check_eq(typeof func, "function");
-  func();
+  do_check_true(fts.processCallback());
 
-  do_check_eq(callbackQueue.length, 0);
+  do_check_false(fts.processCallback());
 }
diff --git a/services/sync/tests/unit/test_async_exceptions.js b/services/sync/tests/unit/test_async_exceptions.js
index f1fe78eadb28..b15a2e8dd666 100644
--- a/services/sync/tests/unit/test_async_exceptions.js
+++ b/services/sync/tests/unit/test_async_exceptions.js
@@ -1,19 +1,8 @@
-const Cu = Components.utils;
-
 Cu.import("resource://weave/util.js");
 Cu.import("resource://weave/async.js");
 
 Function.prototype.async = Async.sugar;
 
-var callbackQueue = [];
-
-Utils.makeTimerForCall = function fake_makeTimerForCall(cb) {
-  // Just add the callback to our queue and we'll call it later, so
-  // as to simulate a real nsITimer.
-  callbackQueue.push(cb);
-  return "fake nsITimer";
-};
-
 function thirdGen() {
   let self = yield;
 
@@ -54,12 +43,8 @@ function runTestGenerator() {
 }
 
 function run_test() {
+  var fts = new FakeTimerService();
   runTestGenerator.async({});
-  let i = 1;
-  while (callbackQueue.length > 0) {
-    let cb = callbackQueue.pop();
-    cb();
-    i += 1;
-  }
-  do_check_eq(i, 5);
+  for (var i = 0; fts.processCallback(); i++) {}
+  do_check_eq(i, 4);
 }
diff --git a/services/sync/tests/unit/test_async_missing_yield.js b/services/sync/tests/unit/test_async_missing_yield.js
index 14347ae518b9..b3ae785627fe 100644
--- a/services/sync/tests/unit/test_async_missing_yield.js
+++ b/services/sync/tests/unit/test_async_missing_yield.js
@@ -1,23 +1,12 @@
-const Cu = Components.utils;
-
 Cu.import("resource://weave/util.js");
 Cu.import("resource://weave/async.js");
 
 Function.prototype.async = Async.sugar;
 
-var callbackQueue = [];
-
-Utils.makeTimerForCall = function fake_makeTimerForCall(cb) {
-  // Just add the callback to our queue and we'll call it later, so
-  // as to simulate a real nsITimer.
-  callbackQueue.push(cb);
-  return "fake nsITimer";
-};
-
 function secondGen() {
   let self = yield;
 
-  callbackQueue.push(self.cb);
+  Utils.makeTimerForCall(self.cb);
 
   self.done();
 }
@@ -32,38 +21,13 @@ function runTestGenerator() {
 }
 
 function run_test() {
-  const Cu = Components.utils;
-
   Cu.import("resource://weave/log4moz.js");
   Cu.import("resource://weave/async.js");
 
-  var errorsLogged = 0;
-
-  function _TestFormatter() {}
-  _TestFormatter.prototype = {
-    format: function BF_format(message) {
-      if (message.level == Log4Moz.Level.Error)
-        errorsLogged += 1;
-      return message.loggerName + "\t" + message.levelDesc + "\t" +
-        message.message + "\n";
-    }
-  };
-  _TestFormatter.prototype.__proto__ = new Log4Moz.Formatter();
-
-  var log = Log4Moz.Service.rootLogger;
-  var formatter = new _TestFormatter();
-  var appender = new Log4Moz.DumpAppender(formatter);
-  log.level = Log4Moz.Level.Trace;
-  appender.level = Log4Moz.Level.Trace;
-  log.addAppender(appender);
+  var fts = new FakeTimerService();
+  var logStats = initTestLogging();
 
   runTestGenerator.async({});
-  let i = 1;
-  while (callbackQueue.length > 0) {
-    let cb = callbackQueue.pop();
-    cb();
-    i += 1;
-  }
-
-  do_check_eq(errorsLogged, 3);
+  while (fts.processCallback()) {};
+  do_check_eq(logStats.errorsLogged, 3);
 }
diff --git a/services/sync/tests/unit/test_sharing.js b/services/sync/tests/unit/test_sharing.js
index b962404e9d37..e18f6de3be95 100644
--- a/services/sync/tests/unit/test_sharing.js
+++ b/services/sync/tests/unit/test_sharing.js
@@ -1,5 +1,3 @@
-const Cu = Components.utils;
-
 Cu.import("resource://weave/sharing.js");
 Cu.import("resource://weave/util.js");
 
diff --git a/services/sync/tests/unit/test_xmpp.js b/services/sync/tests/unit/test_xmpp.js
index 60396b2e054c..9c76eed9308a 100644
--- a/services/sync/tests/unit/test_xmpp.js
+++ b/services/sync/tests/unit/test_xmpp.js
@@ -1,5 +1,3 @@
-var Cu = Components.utils;
-
 Cu.import( "resource://weave/xmpp/xmppClient.js" );
 
 function LOG(aMsg) {