1 files changed, 76 insertions, 0 deletions
diff --git a/services/sync/tests/unit/test_utils_lock.js b/services/sync/tests/unit/test_utils_lock.js
new file mode 100644
index 0000000000..d1827425c2
--- /dev/null
+++ b/services/sync/tests/unit/test_utils_lock.js
@@ -0,0 +1,76 @@
+_("Make sure lock prevents calling with a shared lock");
+
+// Utility that we only use here.
+
+function do_check_begins(thing, startsWith) {
+  if (!(thing && thing.indexOf && thing.indexOf(startsWith) == 0)) {
+    do_throw(thing + " doesn't begin with " + startsWith);
+  }
+}
+
+add_task(async function run_test() {
+  let ret, rightThis, didCall;
+  let state, lockState, lockedState, unlockState;
+  let obj = {
+    _lock: Utils.lock,
+    lock() {
+      lockState = ++state;
+      if (this._locked) {
+        lockedState = ++state;
+        return false;
+      }
+      this._locked = true;
+      return true;
+    },
+    unlock() {
+      unlockState = ++state;
+      this._locked = false;
+    },
+
+    func() {
+      return this._lock("Test utils lock", async function() {
+        rightThis = this == obj;
+        didCall = true;
+        return 5;
+      })();
+    },
+
+    throwy() {
+      return this._lock("Test utils lock throwy", async function() {
+        rightThis = this == obj;
+        didCall = true;
+        return this.throwy();
+      })();
+    },
+  };
+
+  _("Make sure a normal call will call and return");
+  rightThis = didCall = false;
+  state = 0;
+  ret = await obj.func();
+  Assert.equal(ret, 5);
+  Assert.ok(rightThis);
+  Assert.ok(didCall);
+  Assert.equal(lockState, 1);
+  Assert.equal(unlockState, 2);
+  Assert.equal(state, 2);
+
+  _("Make sure code that calls locked code throws");
+  ret = null;
+  rightThis = didCall = false;
+  try {
+    ret = await obj.throwy();
+    do_throw("throwy internal call should have thrown!");
+  } catch (ex) {
+    // Should throw an Error, not a string.
+    do_check_begins(ex.message, "Could not acquire lock");
+  }
+  Assert.equal(ret, null);
+  Assert.ok(rightThis);
+  Assert.ok(didCall);
+  _("Lock should be called twice so state 3 is skipped");
+  Assert.equal(lockState, 4);
+  Assert.equal(lockedState, 5);
+  Assert.equal(unlockState, 6);
+  Assert.equal(state, 6);
+});