<PackageReference Include="NUnit" Version="4.2.2" />

NUnit.Framework.Api.DefaultTestAssemblyBuilder

DefaultTestAssemblyBuilder loads a single assembly and builds a TestSuite containing test fixtures present in the assembly.
namespace NUnit.Framework.Api { public class DefaultTestAssemblyBuilder : ITestAssemblyBuilder { public DefaultTestAssemblyBuilder(); public ITest Build(Assembly assembly, IDictionary<string, object> options); public ITest Build(string assemblyNameOrPath, IDictionary<string, object> options); } }