[sync] Add store version to model type store backend

components/sync/model_impl/model_type_store_backend_unittest.cc

Index: components/sync/model_impl/model_type_store_backend_unittest.cc
diff --git a/components/sync/model_impl/model_type_store_backend_unittest.cc b/components/sync/model_impl/model_type_store_backend_unittest.cc
index bbc8e121d18a7280064683d61ed8b506516ec2fd..29628e0087fe010df1fda2d40a98c463e52cdf6f 100644
--- a/components/sync/model_impl/model_type_store_backend_unittest.cc
+++ b/components/sync/model_impl/model_type_store_backend_unittest.cc
@@ -6,10 +6,13 @@
 
 #include <utility>
 
+#include "components/sync/protocol/model_type_store_schema_descriptor.pb.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/leveldatabase/src/include/leveldb/env.h"
 #include "third_party/leveldatabase/src/include/leveldb/write_batch.h"
 
+using sync_pb::ModelTypeStoreSchemaDescriptor;
+
 namespace syncer {
 
 class ModelTypeStoreBackendTest : public testing::Test {
@@ -48,6 +51,21 @@ class ModelTypeStoreBackendTest : public testing::Test {
   std::string GetBackendPath(scoped_refptr<ModelTypeStoreBackend> backend) {
     return backend->path_;
   }
+
+  bool Migrate(scoped_refptr<ModelTypeStoreBackend> backend,
+               const ModelTypeStoreSchemaDescriptor& current_metadata,
+               const ModelTypeStoreSchemaDescriptor& desired_metadata) {
+    return backend->Migrate(current_metadata, desired_metadata);
+  }
+
+  bool Migrate0To1(scoped_refptr<ModelTypeStoreBackend> backend) {
+    return backend->Migrate0To1();
+  }
+
+  bool GetStoreDescriptor(scoped_refptr<ModelTypeStoreBackend> backend,
+                          ModelTypeStoreSchemaDescriptor* schema_descriptor) {
+    return backend->GetStoreDescriptor(schema_descriptor);
+  }
 };
 
 // Test that after record is written to backend it can be read back even after
@@ -189,4 +207,47 @@ TEST_F(ModelTypeStoreBackendTest, TwoDifferentBackendTest) {
   ASSERT_FALSE(BackendExistsForPath("/test_db2"));
 }
 
+// Test that initializing the database migrates it to the latest schema version.
+TEST_F(ModelTypeStoreBackendTest, MigrateNoSchemaVersionToLatestVersionTest) {
+  scoped_refptr<ModelTypeStoreBackend> backend = GetOrCreateBackend();
+
+  ModelTypeStoreSchemaDescriptor schema_descriptor;
+  ASSERT_TRUE(GetStoreDescriptor(backend, &schema_descriptor));
+  ASSERT_EQ(schema_descriptor.version_number(), kLatestSchemaVersion);
+}
+
+// Test that the 0 to 1 migration succeeds and sets the schema version to 1.
+TEST_F(ModelTypeStoreBackendTest, Migrate0To1Test) {
+  scoped_refptr<ModelTypeStoreBackend> backend = GetOrCreateBackend();
+
+  std::unique_ptr<leveldb::WriteBatch> write_batch(new leveldb::WriteBatch());
+  write_batch->Delete(kDBSchemaDescriptorRecordId);
+  ModelTypeStore::Result result =
+      backend->WriteModifications(std::move(write_batch));
+  ASSERT_EQ(ModelTypeStore::Result::SUCCESS, result);
+
+  ASSERT_TRUE(Migrate0To1(backend));
+
+  ModelTypeStoreSchemaDescriptor schema_descriptor;
+  ASSERT_TRUE(GetStoreDescriptor(backend, &schema_descriptor));
+  ASSERT_EQ(schema_descriptor.version_number(), 1);
+}
+
+// Test that migration to an unknown version fails
+TEST_F(ModelTypeStoreBackendTest, MigrateToBogusVersionFails) {
+  scoped_refptr<ModelTypeStoreBackend> backend = GetOrCreateBackend();
+
+  std::unique_ptr<leveldb::WriteBatch> write_batch(new leveldb::WriteBatch());
+  write_batch->Delete(kDBSchemaDescriptorRecordId);
+  ModelTypeStore::Result result =
+      backend->WriteModifications(std::move(write_batch));
+  ASSERT_EQ(ModelTypeStore::Result::SUCCESS, result);
+
+  ModelTypeStoreSchemaDescriptor current_metadata;
+  current_metadata.set_version_number(0);
+  ModelTypeStoreSchemaDescriptor bogus_desired_metadata;
+  bogus_desired_metadata.set_version_number(999);
+  ASSERT_FALSE(Migrate(backend, current_metadata, bogus_desired_metadata));
+}
+
 }  // namespace syncer