[Sync] USS: Filter out redundant changes in SMTP.

sync/internal_api/shared_model_type_processor_unittest.cc

Index: sync/internal_api/shared_model_type_processor_unittest.cc
diff --git a/sync/internal_api/shared_model_type_processor_unittest.cc b/sync/internal_api/shared_model_type_processor_unittest.cc
index 1e6a7f79ef8dd908d928a7a77c89ea93438f56be..d626e2b36f3caf0a8b3850b9f94b59a2e55c21f6 100644
--- a/sync/internal_api/shared_model_type_processor_unittest.cc
+++ b/sync/internal_api/shared_model_type_processor_unittest.cc
@@ -59,16 +59,25 @@ scoped_ptr<EntityData> CopyEntityData(const EntityData& old_data) {
 class SimpleStore {
  public:
   void PutData(const std::string& tag, const EntityData& data) {
+    data_change_count_++;
     data_store_[tag] = CopyEntityData(data);
   }
 
   void PutMetadata(const std::string& tag,
                    const sync_pb::EntityMetadata& metadata) {
+    metadata_change_count_++;
     metadata_store_[tag] = metadata;
   }
 
-  void RemoveData(const std::string& tag) { data_store_.erase(tag); }
-  void RemoveMetadata(const std::string& tag) { metadata_store_.erase(tag); }
+  void RemoveData(const std::string& tag) {
+    data_change_count_++;
+    data_store_.erase(tag);
+  }
+
+  void RemoveMetadata(const std::string& tag) {
+    metadata_change_count_++;
+    metadata_store_.erase(tag);
+  }
 
   bool HasData(const std::string& tag) const {
     return data_store_.find(tag) != data_store_.end();
@@ -93,6 +102,9 @@ class SimpleStore {
   size_t DataCount() const { return data_store_.size(); }
   size_t MetadataCount() const { return metadata_store_.size(); }
 
+  size_t DataChangeCount() const { return data_change_count_; }
+  size_t MetadataChangeCount() const { return metadata_change_count_; }
+
   const sync_pb::DataTypeState& data_type_state() const {
     return data_type_state_;
   }
@@ -111,12 +123,16 @@ class SimpleStore {
   }
 
   void Reset() {
+    data_change_count_ = 0;
+    metadata_change_count_ = 0;
     data_store_.clear();
     metadata_store_.clear();
     data_type_state_.Clear();
   }
 
  private:
+  size_t data_change_count_ = 0;
+  size_t metadata_change_count_ = 0;
   std::map<std::string, scoped_ptr<EntityData>> data_store_;
   std::map<std::string, sync_pb::EntityMetadata> metadata_store_;
   sync_pb::DataTypeState data_type_state_;
@@ -821,7 +837,7 @@ TEST_F(SharedModelTypeProcessorTest, LocalCreateItem) {
 
 // The purpose of this test case is to test setting |client_tag_hash| and |id|
 // on the EntityData object as we pass it into the Put method of the processor.
-TEST_F(SharedModelTypeProcessorTest, LocalCreateAndModifyWithOverrides) {
+TEST_F(SharedModelTypeProcessorTest, LocalUpdateItemWithOverrides) {
   const std::string kId1 = "cid1";
   const std::string kId2 = "cid2";
   const std::string kName1 = "name1";
@@ -883,7 +899,7 @@ TEST_F(SharedModelTypeProcessorTest, LocalCreateAndModifyWithOverrides) {
 
 // Creates a new local item then modifies it.
 // Thoroughly tests data generated by modification of server-unknown item.
-TEST_F(SharedModelTypeProcessorTest, LocalCreateAndModifyItem) {
+TEST_F(SharedModelTypeProcessorTest, LocalUpdateItem) {
   InitializeToReadyState();
 
   WriteItem(kTag1, kValue1);
@@ -934,6 +950,18 @@ TEST_F(SharedModelTypeProcessorTest, LocalCreateAndModifyItem) {
   EXPECT_NE(metadata_v1.specifics_hash(), metadata_v2.specifics_hash());
 }
 
+// Tests that a local update that doesn't change specifics doesn't generate a
+// commit request.
+TEST_F(SharedModelTypeProcessorTest, LocalUpdateItemRedundant) {
+  InitializeToReadyState();
+  WriteItem(kTag1, kValue1);
+  EXPECT_EQ(1U, db().MetadataCount());
+  ExpectCommitRequests({kTag1});
+
+  WriteItem(kTag1, kValue1);
+  ExpectCommitRequests({kTag1});
+}
+
 // Thoroughly tests the data generated by a server item creation.
 TEST_F(SharedModelTypeProcessorTest, ServerCreateItem) {
   InitializeToReadyState();
@@ -964,6 +992,26 @@ TEST_F(SharedModelTypeProcessorTest, ServerCreateItem) {
   EXPECT_TRUE(metadata.has_specifics_hash());
 }
 
+// Thoroughly tests the data generated by a server item creation.
+TEST_F(SharedModelTypeProcessorTest, ServerUpdateItem) {
+  InitializeToReadyState();
+
+  // Local add writes data and metadata; ack writes metadata again.
+  WriteItemAndAck(kTag1, kValue1);
+  EXPECT_EQ(1U, db().DataChangeCount());
+  EXPECT_EQ(2U, db().MetadataChangeCount());
+
+  // Redundant update from server doesn't write data but updates metadata.
+  UpdateFromServer(5, kTag1, kValue1);
+  EXPECT_EQ(1U, db().DataChangeCount());
+  EXPECT_EQ(3U, db().MetadataChangeCount());
+
+  // A reflection (update already received) is ignored completely.
+  UpdateFromServer(0 /* version_offset */, kTag1, kValue1);
+  EXPECT_EQ(1U, db().DataChangeCount());
+  EXPECT_EQ(3U, db().MetadataChangeCount());
+}
+
 // Tests locally deleting an acknowledged item.
 TEST_F(SharedModelTypeProcessorTest, LocalDeleteItem) {
   InitializeToReadyState();