<PackageReference Include="NUnit" Version="4.3.2" />

NUnit.Framework.Interfaces.IFixtureBuilder

public interface IFixtureBuilder
The IFixtureBuilder interface is exposed by a class that knows how to build test fixtures from a specified type. In general, it is exposed by an attribute, but it may be implemented in a helper class used by the attribute in some cases.
namespace NUnit.Framework.Interfaces { public interface IFixtureBuilder { IEnumerable<TestSuite> BuildFrom(ITypeInfo typeInfo); } }