Can't create unit test project - 'VisualStudio.Extensibility projects must contribute one clsas extending Microsoft.VisualStudio.Extensibility.Extension'

[luislhg]

Hello, I have an extension using the new Extensibility SDK.
I have some services in there, and when trying to create an unit test project I receive this error and can't build

[luislhg]

As a workaround, I faked a class in the unit test project and it seems to work.

[VisualStudioContribution]
internal class MockEntrypoint : Extension
{
    public override ExtensionConfiguration ExtensionConfiguration => null;
}