Using NUnit with VS2010 Beta and .NET Framework 4.0

I've been test driving Visual Studio 2010 Beta recently and it comes with, and defaults to, .NET Framework 4.0, exciting stuff all around until you realize that if you target the 4.0 Framework you end up with this when trying to run your tests. Let's call this, less than helpful. Some googling turns up one solution, rebuild NUnit from source. Now while that is a viable solution you should never just go for the first solution that enters your mind. After some pondering I came to think of the metadata storage signature defintion present in all .NET Assemblies and how it actually does contain the desired framework version.

Using your hexeditor of choice (I like XVI32) simply open "nunit.exe" and search for "v2" it should turn up something like the screenshot below:

Notice the "BSJB" just preceding the version string, that's the metadata signature basically telling us we're in the right place. Now change "v2.0.50727" into "v4.0.20506" save and start NUnit. It will now run under the 4.0 framework instead, happily running your tests.

Oh, if you think that't both rebuilding from source, and hacking metadata is maybe not really "the right solution (tm)" you could just configure it instead.