mandoline filesystem: add a sqlite3 vfs to proxy filesystem usage.

sql/mojo/sql_test_base.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SQL_MOJO_SQL_TEST_BASE_H_
+#define SQL_MOJO_SQL_TEST_BASE_H_
+
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/filesystem/public/interfaces/file_system.mojom.h"
+#include "mojo/application/public/cpp/application_test_base.h"
+#include "sql/connection.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace sql {
+
+class Connection;
+class ScopedMojoFilesystemVFS;
+
+// Base class for SQL tests.
+//
+// WARNING: We want to run the same gtest based unit test code both against
+// chromium (which uses this implementation here), and the mojo code (which
+// uses a different class named SQLTestBase). These two classes need to have
+// the same interface because we compile time switch them based on a
+// #define. We need to have two different implementations because the mojo
+// version derives from mojo::test::ApplicationTestBase instead of
+// testing::Test.
+class SQLTestBase : public mojo::test::ApplicationTestBase {
+ public:
+  SQLTestBase();
+  ~SQLTestBase() override;
+
+  enum WriteJunkType {
+    TYPE_TRUNCATE_AND_CREATE,
+    TYPE_OPEN_NORMALLY

[Scott Hess - ex-Googler, 2015/06/19 20:48:02]

How about TYPE_OVERWRITE and TYPE_OVERWRITE_AND_TRUNCATE?  I believe the file
already exists in both cases, and the operation is more similar than the current
naming maybe indicates.

Another alternative would be WriteJunkDatabase vs WriteJunkToDatabase (or Into)
as function names and not bother with the additional type.

+  };
+
+  // Returns the path to the database.
+  base::FilePath db_path();
+
+  // Returns a connection to the database at db_path().
+  sql::Connection& db();
+
+  // Closes the current connection to the database and reopens it.
+  bool Reopen();
+
+  // Proxying method around base::PathExists.
+  bool GetPathExists(const base::FilePath& path);
+
+  // SQLite stores the database size in the header, and if the actual
+  // OS-derived size is smaller, the database is considered corrupt.
+  // [This case is actually a common form of corruption in the wild.]
+  // This helper sets the in-header size to one page larger than the
+  // actual file size.  The resulting file will return SQLITE_CORRUPT
+  // for most operations unless PRAGMA writable_schema is turned ON.
+  //
+  // Returns false if any error occurs accessing the file.
+  bool CorruptSizeInHeaderOfDB();
+
+  // Writes junk to the start of the file.
+  void WriteJunkToDatabase(WriteJunkType type);
+
+  // Sets the database file size to 0.
+  void TruncateDatabase();
+
+  // Overridden from testing::Test:
+  void SetUp() override;
+  void TearDown() override;
+
+ protected:
+  filesystem::FileSystemPtr& files() { return files_; }
+
+ private:
+  filesystem::FileSystemPtr files_;
+
+  scoped_ptr<ScopedMojoFilesystemVFS> vfs_;
+  sql::Connection db_;
+
+  DISALLOW_COPY_AND_ASSIGN(SQLTestBase);
+};
+
+}  // namespace sql
+
+#endif  // SQL_MOJO_SQL_TEST_BASE_H_