Add crossplatform tests that cause Path.GetFullPath to throw

[cdmihai]

With PR #632, we are swapping out MSBuild's implementation of Path.GetFullPath with the one in .net.

More tests are needed that cause Path.GetFullPath to throw an exception on Linux and OSX, when the method is called from an item function. The current tests for this scenario are windows only: #632 (diff). Since Unix paths accept everything but / and /0, it might be tricky to make it fail. Maybe take away file permissions?

[rainersigwald]

HFS+ (OS X) paths disallow :, so there's a test case. For Linux paths maybe this is meaningless.

[cdmihai]

On OSX I just tried touch a:b and it created the file. echo "hello" > a:b also works
Don't know what .Net Core actually does.

[radical]

We have some tests here. Look for GetFullPath* .

[coderpatros]

I take it no one is working on this already?

The tests @radical reference target all platforms within the same unit test. The tests I've seen in msbuild code have platform specific unit tests when required. Can anyone give me some guidance on the preferred approach before I start porting the tests over?

[cdmihai]

Go ahead and remove the PlatformSpecific part, and switch the minimum test data based based on the OS, at the beginning of the tests. You don't have to port verbatim, because we're not testing Path.GetFullPath. Just the tests exercising msbuild item functions from #632 (diff)