private void TryReplace(string input, string pageId, string replacement, string expectedOutput) { using (var inputStream = new StreamReader(new MemoryStream(Encoding.UTF8.GetBytes(input)))) using (var output = new MemoryStream()) using (var outputStream = new StreamWriter(output)) { BookStorage.ReplacePage(pageId, inputStream, outputStream, replacement); outputStream.Flush(); output.Position = 0; string result = new StreamReader(output).ReadToEnd(); Assert.That(result, Is.EqualTo(expectedOutput)); } }