Wow! That is confusing. I'll go back and clean up the links so you can
at least get to the last stop in a single jump.
NUnit and NUnitLite were once separate projects. NUnit gave birth to
NUnitLite, then NUnitLite influenced NUnit, etc. The last releases of
that old era were NUnit 2.6.3 and NUnitLite 1.0.
Future releases of NUnitLite will be built from a common source code
base along with NUnit. We call that NUnit 3.0. Up to now, we are still
pre-alpha and we are using the 2.9.x series to represent "almost 3.0"
The last binary release was NUnit 2.9.6 and the current source code is
on GitHub in the nunit.framework project.
As far as your question... I'm not sure. When you talk about the
"Xamarin Runner" what do you mean? Is it the NUnit addin for
MonoDevelop? That uses whatever version of NUnit (not NUnitLite) the
Xamarin guys last imported. AFAIK, you can't change the version, but I
could be wrong there.
OTOH, if you are developing for the IPad or IPhone, the Xamarin guys
have a special build of NUnitLite that works with that platform. They
have another special build that works with Android. You may need to
ask them for more info about it. If you find out more from another
source, I hope you'll post it here!