<PackageReference Include="NUnit" Version="4.5.1" />

NUnit.Framework.TestAssemblyDirectoryResolveAttribute

Marks a test assembly as needing a special assembly resolution hook that will explicitly search the test assembly's directory for dependent assemblies. This works around a conflict between mixed-mode assembly initialization and tests running in their own AppDomain in some cases.
namespace NUnit.Framework { public class TestAssemblyDirectoryResolveAttribute : NUnitAttribute { public TestAssemblyDirectoryResolveAttribute(); } }