<p>I have  a heap of unit tests that need to check XML outputs.</p>

<p>I have started out comparing strings but this isn't going to scale as formatting and superficial differences get in the way.</p>

<p>What is the easiest way in .NET to evaluate whether the generated XML is semantically the same as what the test expects?</p>

<blockquote>
  <p><strong>Closed</strong> as duplicate of <a href="https://stackoverflow.com/questions/167946/how-would-you-compare-two-xml-documents">How would you compare two XML Documents?</a></p>
</blockquote>

Microsoft offers its XML Diff tools/classes
here
. I haven't personally used it, but it sounds like it'll get you started:
"By using the XMLDiff class, the
  programmer is able to determine if the
  two files are in fact different based
  on the conditions that are important
  to their application"
It seems to cope with different ordering, spacing, namespace prefixes etc.