How to add external plugin dll to edit mode test assembly?

I have built a .NET Standard 2.1 class library in Visual Studio 2022, and placed the output dll into the Unity project’s plugin folder. While I am able to use the dll in my game, I cannot get editor mode test scripts to reference the dll objects.

I have an editor mode test asmdef file, and I can reference other asmdef file in the Unity project, but there seems no way to add reference to the plugin dll.

What can I do to use the plugin dll code in edit mode test?

Thanks.

This is explained here.

You need to turn on Override References and then you should be able to pick your DLL from a dropdown.