diff -r 000000000000 -r 6474c204b198 services/sync/tests/unit/test_utils_catch.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/services/sync/tests/unit/test_utils_catch.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,86 @@
+Cu.import("resource://services-sync/util.js");
+Cu.import("resource://services-sync/service.js");
+
+function run_test() {
+  _("Make sure catch when copied to an object will correctly catch stuff");
+  let ret, rightThis, didCall, didThrow, wasTen, wasLocked;
+  let obj = {
+    catch: Utils.catch,
+    _log: {
+      debug: function(str) {
+        didThrow = str.search(/^Exception: /) == 0;
+      },
+      info: function(str) {
+        wasLocked = str.indexOf("Cannot start sync: already syncing?") == 0;
+      }
+    },
+
+    func: function() this.catch(function() {
+      rightThis = this == obj;
+      didCall = true;
+      return 5;
+    })(),
+
+    throwy: function() this.catch(function() {
+      rightThis = this == obj;
+      didCall = true;
+      throw 10;
+    })(),
+
+    callbacky: function() this.catch(function() {
+      rightThis = this == obj;
+      didCall = true;
+      throw 10;
+    }, function(ex) {
+      wasTen = (ex == 10)
+    })(),
+
+    lockedy: function() this.catch(function() {
+      rightThis = this == obj;
+      didCall = true;
+      throw("Could not acquire lock.");
+    })()
+  };
+
+  _("Make sure a normal call will call and return");
+  rightThis = didCall = didThrow = wasLocked = false;
+  ret = obj.func();
+  do_check_eq(ret, 5);
+  do_check_true(rightThis);
+  do_check_true(didCall);
+  do_check_false(didThrow);
+  do_check_eq(wasTen, undefined);
+  do_check_false(wasLocked);
+
+  _("Make sure catch/throw results in debug call and caller doesn't need to handle exception");
+  rightThis = didCall = didThrow = wasLocked = false;
+  ret = obj.throwy();
+  do_check_eq(ret, undefined);
+  do_check_true(rightThis);
+  do_check_true(didCall);
+  do_check_true(didThrow);
+  do_check_eq(wasTen, undefined);
+  do_check_false(wasLocked);
+
+  _("Test callback for exception testing.");
+  rightThis = didCall = didThrow = wasLocked = false;
+  ret = obj.callbacky();
+  do_check_eq(ret, undefined);
+  do_check_true(rightThis);
+  do_check_true(didCall);
+  do_check_true(didThrow);
+  do_check_true(wasTen);
+  do_check_false(wasLocked);
+
+  _("Test the lock-aware catch that Service uses.");
+  obj.catch = Service._catch;
+  rightThis = didCall = didThrow = wasLocked = false;
+  wasTen = undefined;
+  ret = obj.lockedy();
+  do_check_eq(ret, undefined);
+  do_check_true(rightThis);
+  do_check_true(didCall);
+  do_check_true(didThrow);
+  do_check_eq(wasTen, undefined);
+  do_check_true(wasLocked);
+}