public void write()
{
byte[] actual = testData.ToArray();
MemoryStream memStream = new MemoryStream(actual, true);
memStream.Seek(testDataOffset, SeekOrigin.Current);
RangeStream rangeStream = new RangeStream(memStream, 4, true);
byte[] expected = testData.ToArray();
expected[testDataOffset + 0] = 0x10;
expected[testDataOffset + 1] = 0x20;
expected[testDataOffset + 2] = 0x30;
expected[testDataOffset + 3] = 0x40;
rangeStream.Write(expected, testDataOffset, testDataLength);
Assert.AreEqual(expected, actual);
}