I tried to upgrade Nunit 3->4. Now my IDE cannot see any tests.
I have investigated proj files, delved through nuget packages/versions and looked at the documentation.
The tests can be run through the cli dotnet test -v=normal
My IDE is Rider on a Mac m2.
This is a known issue, you have to use Rider 2023.3. I filed an issue at JetBrains and the answer was:
Rider 2023.2 does not support NUnit 4. Please update to Rider 2023.3 where it is fully supported.