Using examples in publifications

NUnit is open source, with version 2.x under a variant of the zlib/libphp license.
So you are free to use the nunit code in various ways.

The documentation that comes with it - the html files - are not mainly code and are
not under any open source of creative commons license. They are copyright to me
personally and I'm not inclined to allow their use (beyond "fair use" in the US) for
somebody else's book.

BTW, the example code in the documentation is very simplistic, and I will not be
using much of it in my own book. People want better, more extended and more
realistic examples, in my opinion.

Regarding the logo, you can use it in certain ways and not in others. For example,
if you used it in a way that suggested the book was made by or approved by
the NUnit team, that would be wrong and we would insist that your publisher
remove it. Using it in images that show the NUnit screen is allowed, of course,
and there are probably other ways that it might be used under the notion
of "fair use" - at least in the US, where the concept is recognized.

Frankly, your publisher has lawyers to figure this out. Show them my answer and
they will tell you how to ask for the permission you need. If you do need to ask
for special permission to do something, please contact me offline with the details,
rather than through a public posting.
(Charlie AT NUnit DOT org)