This is a sample repo to reproduce NUnit.ENgine 3.12.0 assemblies load issues on .NET Core (cf. nunit.console-#942).

Run tests

In order to run the test using NUnit.Engine 3.12.0 (assuming you already run dotnet build), you will need to use NUnit.ConsoleRunner.NetCore 3.12.0-beta*(beta1 or beta2) NuGet package. For that add this package as a dependency to one of your projects and perform a dotnet restore (or you could try with Get-PackageProvider). Once the package is restored (mine was at C:\Users\brekhadd020117\.nuget ), locate it and run:

C:\Users\brekhadd020117\.nuget\packages\nunit.consolerunner.netcore\3.12.0-beta1\tools\nunit3-console.exe <path_to_clone>\nunit-sample\.build\bin\Debug\netcoreapp3.1\UnitTests.dll

Excpected behavior

Test Run Summary Overall result: Passed Test Count: 1, Passed: 1, Failed: 0, Warnings: 0, Inconclusive: 0, Skipped: 0

Actual behavior

Error : UnitTests.EmitDemo.Test_EmiCompilation System.Exception : Type 'DummyNamespace.Helper' could not be found at UnitTests.EmitDemo.CalculateSum(Double a, Double b) in D:\git\nunit-sample\UnitTests\EmitDemo.cs:line 83 at UnitTests.EmitDemo.Test_EmiCompilation() in D:\git\nunit-sample\UnitTests\EmitDemo.cs:line 99

Attempt of fix

Since NUnit is using a custom AssemblyLoadContext, I've tried to force my assmeblies load in this custom context, and it worked!

Code snippet added:

var nunitCustomAssemblyLoadContext = AssemblyLoadContext.All.Single(c => c.ToString().Contains("NUnit.Engine.Internal.CustomAssemblyLoadContext"));
var asm = nunitCustomAssemblyLoadContext.LoadFromAssemblyPath(path);