Add integraton test for sync backup/rollback.

sync/test/fake_server/fake_server.cc

Index: sync/test/fake_server/fake_server.cc
diff --git a/sync/test/fake_server/fake_server.cc b/sync/test/fake_server/fake_server.cc
index 207f1a2700115ac0a726f33bb5440e9e58641cdb..eb75886c8da91e03dd4a7495708dcf8375c0018a 100644
--- a/sync/test/fake_server/fake_server.cc
+++ b/sync/test/fake_server/fake_server.cc
@@ -145,7 +145,9 @@ scoped_ptr<UpdateSieve> UpdateSieve::Create(
 
 }  // namespace
 
-FakeServer::FakeServer() : version_(0), birthday_(kDefaultBirthday) {
+FakeServer::FakeServer() : version_(0),
+                           birthday_(kDefaultBirthday),
+                           error_type_(sync_pb::SyncEnums::SUCCESS) {
   keystore_keys_.push_back(kDefaultKeystoreKey);
   CHECK(CreateDefaultPermanentItems());
 }
@@ -220,19 +222,24 @@ void FakeServer::HandleCommand(const string& request,
 
   sync_pb::ClientToServerResponse response_proto;
   bool success;
-  switch (message.message_contents()) {
-    case sync_pb::ClientToServerMessage::GET_UPDATES:
-      success = HandleGetUpdatesRequest(message.get_updates(),
-                                        response_proto.mutable_get_updates());
-      break;
-    case sync_pb::ClientToServerMessage::COMMIT:
-      success = HandleCommitRequest(message.commit(),
-                                    message.invalidator_client_id(),
-                                    response_proto.mutable_commit());
-      break;
-    default:
-      callback.Run(net::ERR_NOT_IMPLEMENTED, 0, string());;
-      return;
+
+  if (error_type_ != sync_pb::SyncEnums::SUCCESS) {

[pval...(no longer on Chromium), 2014/06/03 22:08:18]

there are a few other in-flight changes here that might make merging difficult.
would you like me to commit the TriggerError infrastructure so that you don't
have to deal with it?

[haitaol1, 2014/06/04 18:21:30]

I rebased on ToT. Please take a look to verify.

On 2014/06/03 22:08:18, pvalenzuela wrote:

[pval...(no longer on Chromium), 2014/06/05 17:46:14]

latest version (patchset 5) looks good

+    success = true;
+  } else {
+    switch (message.message_contents()) {
+      case sync_pb::ClientToServerMessage::GET_UPDATES:
+        success = HandleGetUpdatesRequest(message.get_updates(),
+                                          response_proto.mutable_get_updates());
+        break;
+      case sync_pb::ClientToServerMessage::COMMIT:
+        success = HandleCommitRequest(message.commit(),
+                                      message.invalidator_client_id(),
+                                      response_proto.mutable_commit());
+        break;
+      default:
+        callback.Run(net::ERR_NOT_IMPLEMENTED, 0, string());;
+        return;
+    }
   }
 
   if (!success) {
@@ -242,8 +249,8 @@ void FakeServer::HandleCommand(const string& request,
     return;
   }
 
-  response_proto.set_error_code(sync_pb::SyncEnums::SUCCESS);
   response_proto.set_store_birthday(birthday_);
+  response_proto.set_error_code(error_type_);
   callback.Run(0, net::HTTP_OK, response_proto.SerializeAsString());
 }
 
@@ -473,6 +480,10 @@ void FakeServer::InjectEntity(scoped_ptr<FakeServerEntity> entity) {
   SaveEntity(entity.release());
 }
 
+void FakeServer::TriggerError(const sync_pb::SyncEnums::ErrorType& error_type) {

[rlarocque, 2014/06/03 22:59:48]

I think we should look at mock_connection_manager.cc and take it as a warning. 
This style of injecting errors works when there's one or two conditions we care
about, but it can eventually lead to a hairball once we have many different
conditions and triggering logic.

This is OK for now, but we should keep an eye on this style of error injection
to make sure it doesn't get out of control.

[haitaol1, 2014/06/04 18:21:30]

Added a todo for Patrick.

On 2014/06/03 22:59:48, rlarocque wrote:

[pval...(no longer on Chromium), 2014/06/05 17:46:14]

Great; thanks for TODO. I'll clean this up in a later CL.

+  error_type_ = error_type;
+}
+
 void FakeServer::AddObserver(Observer* observer) {
   observers_.AddObserver(observer);
 }