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

Contains

public class Contains
Helper class with properties and methods that supply a number of constraints used in Asserts.
using NUnit.Framework.Constraints; namespace NUnit.Framework { public class Contains { public static EqualConstraint Item(object expected) { return Has.Some.EqualTo(expected); } public static DictionaryContainsKeyConstraint Key(object expected) { return new DictionaryContainsKeyConstraint(expected); } public static DictionaryContainsValueConstraint Value(object expected) { return new DictionaryContainsValueConstraint(expected); } public static SubstringConstraint Substring(string expected) { return new SubstringConstraint(expected); } } }