public void TestFindPreambleHeaderBlockNotFirstShouldThrow() { using (MemoryStream testStream = new MemoryStream()) { AxCrypt1Guid.Write(testStream); VersionHeaderBlock versionHeaderBlock = new VersionHeaderBlock(); versionHeaderBlock.Write(testStream); PreambleHeaderBlock preambleHeaderBlock = new PreambleHeaderBlock(); preambleHeaderBlock.Write(testStream); testStream.Position = 0; using (AxCryptReader axCryptReader = AxCryptReader.Create(testStream)) { Assert.That(axCryptReader.Read(), Is.True, "We should be able to read the Guid"); Assert.That(axCryptReader.CurrentItemType, Is.EqualTo(AxCryptItemType.MagicGuid), "We're expecting to have found a MagicGuid"); Assert.Throws<FileFormatException>(() => axCryptReader.Read()); } } }