How do I cover this method? Copy stream content to a second stream

Question

I have the following method, it is an extension method and can be called by any Stream object. The method should copy the exact content of a Stream into another Stream.

public static void CopyTo(this Stream input, Stream output)
{
   const int size = 10;
   int num;
   var buffer = new byte[size];
   input.Position = 0;
   while ((num = input.Read(buffer, 0, buffer.Length)) != 0)
   {
      output.Write(buffer, 0, num);
   }
}

I have created one simple test to verify that the content of the original Stream is equal to the content of the final Stream:

[TestMethod]
public void StreamWithContentShouldCopyToAnotherStream()
{
    // arrange
    var content = @"abcde12345";
    byte[] data = Encoding.Default.GetBytes(content);
    var stream = new MemoryStream(data);
    var expectedStream = new MemoryStream();
    // act
    stream.CopyTo(expectedStream);
    // assert
    expectedStream.Length
       .Should()
       .Be(stream.Length, "The length of the two streams should be the same");
}

Unfortunately I am covering just part of this method, because I don't verify if the content is exactly the same. Also dotCover is showing me that the first part of my code is not covered at all, which is this one:

My target is 100% code coverage on this method.

Answer 1

Perhaps your code is not calling your extension method but is instead calling the Stream.CopyTo(Stream) Method?

Try renaming your extension method to avoid the name clash.