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

NUnit.Framework.Constraints.IndexerOperator

Operator used to test for the presence of a Indexer on an object and optionally apply further tests to the value of that indexer.
namespace NUnit.Framework.Constraints { public class IndexerOperator : PrefixOperator { public IndexerOperator(params object[] indexArgs); } }