Fix ILVerify Default Method Verification

[bbartels]

Fixes #46236

The fix involves checking whether an interface method has a method body, as opposed to static, to avoid the search for an implementation in a child class.

I think the ILVerify building/testing workflow should be documented somewhere. It took me quite some time to figure out that the tests were only built when using priority=1.
Furthermore, I ran into the issue of running dotnet test in the ILVerify tests folder. This supposedly permanently breaks your build until you clean all artifacts and recompile (#43967).
Finding and fixing the issue took about half an hour, managing to get the tests working as a first time contributor to the ILVerify tool took about 4 hours.

[am11]

managing to get the tests working as a first time contributor to the ILVerify tool took about 4 hours

Agreed, finding the solution for CS0234 error was not obvious, and took some time to figure out. I ended up with a little handrolled bash script to run a specific test after changing code and rebuilding the source and tests. Basically simulated this workflow for ILVerification project:

runtime/docs/workflow/testing/libraries/testing.md

Line 46 in 1d9e50c

#### Running a single test on the command line

[bbartels]

@am11
Honestly don't think I would have been able to resolve this without your issue. I don't have the most powerful PC so simply building .\build.cmd -c Release takes about 40 minutes. So I was very opposed to the idea of rebuilding if there was still a chance of fixing it without.

[bbartels]

If I were to submit a PR to document the way to build this project should this be in docs/ or src/coreclr/tools/ilverify?
(Assuming this is desired in the first place)

[jkotas]

Thank you!

[jkotas]

If I were to submit a PR to document the way to build this project

This would be much appreciated!

hould this be in docs/ or src/coreclr/tools/ilverify

The documentation is in https://github.com/dotnet/runtime/blob/master/src/coreclr/tools/ILVerify/README.md currently. I think it would be best to keep updating this document with ILVerify specific testing instructions.

[bbartels]

@jkotas should a separate PR be preferable or shall I append it to this one?

[jkotas]

Could you please submit a new PR with the documentation changes?