<PackageReference Include="NUnit" Version="3.8.0" />

NonTestAssemblyAttribute

The NonTestAssemblyAttribute may be used by third-party frameworks or other software that references the nunit framework but does not contain tests. Applying the attribute indicates that the assembly is not a test assembly and may prevent errors if certain runners attempt to load the assembly. Note that recognition of the attribute depends on each individual runner.
using System; using System.ComponentModel; namespace NUnit.Framework { [EditorBrowsable(EditorBrowsableState.Never)] [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = false, Inherited = false)] public class NonTestAssemblyAttribute : NUnitAttribute { } }