public void OpenWriteTest()
        {
            var path = @"z:\temp\aaa.txt";
            var text = "あいうえお";

            var file = new FileEmu();

            using (Stream stream = file.OpenWrite(path))
            {
                byte[] data = Encoding.GetEncoding("shift-jis").GetBytes(text);
                stream.Write(data, 0, data.Length);
            }

            Assert.AreEqual(text, file.ReadAllText(path, Encoding.GetEncoding("shift-jis")));
        }