<PackageReference Include="NUnit" Version="4.4.0-beta.2.1" />

Contains

public abstract class Contains
Helper class with properties and methods that supply a number of constraints used in Asserts.
using NUnit.Framework.Constraints; using System.Runtime.CompilerServices; namespace NUnit.Framework { [System.Runtime.CompilerServices.NullableContext(1)] [System.Runtime.CompilerServices.Nullable(0)] public abstract class Contains { public static SomeItemsConstraint Item([System.Runtime.CompilerServices.Nullable(2)] object expected) { return new SomeItemsConstraint(new EqualConstraint(expected)); } [System.Runtime.CompilerServices.NullableContext(2)] [return: System.Runtime.CompilerServices.Nullable(1)] public static SomeItemsConstraint<T> Item<T>(T expected) { return new SomeItemsConstraint<T>(new EqualConstraint<T>((object)expected)); } public static DictionaryContainsKeyConstraint Key(object expected) { return new DictionaryContainsKeyConstraint(expected); } public static DictionaryContainsValueConstraint Value([System.Runtime.CompilerServices.Nullable(2)] object expected) { return new DictionaryContainsValueConstraint(expected); } public static SubstringConstraint Substring(string expected) { return new SubstringConstraint(expected); } } }