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

NUnit.Framework.Constraints.CollectionConstraint

public abstract class CollectionConstraint : Constraint
CollectionConstraint is the abstract base class for constraints that operate on collections.
namespace NUnit.Framework.Constraints { public abstract class CollectionConstraint : Constraint { protected CollectionConstraint(); protected CollectionConstraint(object arg); protected static bool IsEmpty(IEnumerable enumerable); protected abstract bool Matches(IEnumerable collection); } }