Introduce AttachmentStore metadata record

sync/internal_api/attachments/on_disk_attachment_store_unittest.cc

Index: sync/internal_api/attachments/on_disk_attachment_store_unittest.cc
diff --git a/sync/internal_api/attachments/on_disk_attachment_store_unittest.cc b/sync/internal_api/attachments/on_disk_attachment_store_unittest.cc
index 3479b80f182bd35ededbe14c86315a482ba105a1..ded5f0a2ef2a3b029c62e778d570e192f86fb8eb 100644
--- a/sync/internal_api/attachments/on_disk_attachment_store_unittest.cc
+++ b/sync/internal_api/attachments/on_disk_attachment_store_unittest.cc
@@ -12,7 +12,12 @@
 #include "base/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "sync/internal_api/attachments/attachment_store_test_template.h"
+#include "sync/internal_api/attachments/proto/attachment_store.pb.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/leveldatabase/src/include/leveldb/db.h"
+#include "third_party/leveldatabase/src/include/leveldb/options.h"
+#include "third_party/leveldatabase/src/include/leveldb/slice.h"
+#include "third_party/leveldatabase/src/include/leveldb/status.h"
 
 namespace syncer {
 
@@ -78,6 +83,32 @@ class OnDiskAttachmentStoreSpecificTest : public testing::Test {
     CopyResult(destination_result, source_result);
   }
 
+  scoped_ptr<leveldb::DB> OpenLevelDB(const base::FilePath& path) {
+    leveldb::DB* db;
+    leveldb::Options options;
+    options.create_if_missing = true;
+    leveldb::Status s = leveldb::DB::Open(options, path.AsUTF8Unsafe(), &db);
+    EXPECT_TRUE(s.ok());
+    return make_scoped_ptr(db);
+  }
+
+  void UpdateStoreMetadataRecord(const base::FilePath& path,
+                                 const std::string& content) {
+    scoped_ptr<leveldb::DB> db = OpenLevelDB(path);
+    leveldb::Status s =
+        db->Put(leveldb::WriteOptions(), "database-metadata", content);
+    EXPECT_TRUE(s.ok());
+  }
+
+  std::string ReadStoreMetadataRecord(const base::FilePath& path) {
+    scoped_ptr<leveldb::DB> db = OpenLevelDB(path);
+    std::string content;
+    leveldb::Status s =
+        db->Get(leveldb::ReadOptions(), "database-metadata", &content);
+    EXPECT_TRUE(s.ok());
+    return content;
+  }
+
   void RunLoop() {
     base::RunLoop run_loop;
     run_loop.RunUntilIdle();
@@ -140,8 +171,8 @@ TEST_F(OnDiskAttachmentStoreSpecificTest, FailToOpen) {
       temp_dir_.path().Append(FILE_PATH_LITERAL("leveldb"));
   base::CreateDirectory(db_path);
 
-  // To simulate corrupt database write garbage to CURRENT file.
-  std::string current_file_content = "abra.cadabra";
+  // To simulate corrupt database write empty CURRENT file.
+  std::string current_file_content = "";
   base::WriteFile(db_path.Append(FILE_PATH_LITERAL("CURRENT")),
                   current_file_content.c_str(),
                   current_file_content.size());
@@ -156,4 +187,61 @@ TEST_F(OnDiskAttachmentStoreSpecificTest, FailToOpen) {
   EXPECT_EQ(store_.get(), nullptr);
 }
 
+// Ensure that attachment store works correctly when store metadata is missing,
+// corrupt or has unknown schema version.
+TEST_F(OnDiskAttachmentStoreSpecificTest, StoreMetadata) {
+  ASSERT_TRUE(temp_dir_.CreateUniqueTempDir());
+  base::FilePath db_path =
+      temp_dir_.path().Append(FILE_PATH_LITERAL("leveldb"));
+  base::CreateDirectory(db_path);
+
+  // Create and close empty database.
+  OpenLevelDB(db_path);
+  // Open database with AttachmentStore.
+  AttachmentStore::Result result = AttachmentStore::UNSPECIFIED_ERROR;
+  AttachmentStore::CreateOnDiskStore(
+      temp_dir_.path(),
+      base::ThreadTaskRunnerHandle::Get(),
+      base::Bind(&AttachmentStoreCreated, &store_, &result));
+  RunLoop();
+  EXPECT_EQ(result, AttachmentStore::SUCCESS);
+  // Close AttachmentStore so that test can check content.
+  store_ = nullptr;
+  RunLoop();
+
+  // AttachmentStore should create metadata record.
+  std::string data = ReadStoreMetadataRecord(db_path);
+  attachment_store_pb::AttachmentStoreMetadata metadata;
+  EXPECT_TRUE(metadata.ParseFromString(data));
+  EXPECT_EQ(metadata.schema_version(), 1);
+
+  // Set unknown future schema version.
+  metadata.set_schema_version(2);
+  data = metadata.SerializeAsString();
+  UpdateStoreMetadataRecord(db_path, data);
+
+  // AttachmentStore should fail to load.
+  result = AttachmentStore::SUCCESS;
+  AttachmentStore::CreateOnDiskStore(
+      temp_dir_.path(),
+      base::ThreadTaskRunnerHandle::Get(),
+      base::Bind(&AttachmentStoreCreated, &store_, &result));
+  RunLoop();
+  EXPECT_EQ(result, AttachmentStore::UNSPECIFIED_ERROR);
+  EXPECT_EQ(store_.get(), nullptr);
+
+  // Write garbage into metadata record.
+  UpdateStoreMetadataRecord(db_path, "abra.cadabra");
+
+  // AttachmentStore should fail to load.
+  result = AttachmentStore::SUCCESS;
+  AttachmentStore::CreateOnDiskStore(
+      temp_dir_.path(),
+      base::ThreadTaskRunnerHandle::Get(),
+      base::Bind(&AttachmentStoreCreated, &store_, &result));
+  RunLoop();
+  EXPECT_EQ(result, AttachmentStore::UNSPECIFIED_ERROR);
+  EXPECT_EQ(store_.get(), nullptr);
+}
+
 }  // namespace syncer