<PackageReference Include="NUnit" Version="3.2.0" />

Is

public class Is
Helper class with properties and methods that supply a number of constraints used in Asserts.
using NUnit.Framework.Constraints; using System; using System.Collections; namespace NUnit.Framework { public class Is { public static ConstraintExpression Not => new ConstraintExpression().Not; public static ConstraintExpression All => new ConstraintExpression().All; public static NullConstraint Null => new NullConstraint(); public static TrueConstraint True => new TrueConstraint(); public static FalseConstraint False => new FalseConstraint(); public static GreaterThanConstraint Positive => new GreaterThanConstraint(0); public static LessThanConstraint Negative => new LessThanConstraint(0); public static EqualConstraint Zero => new EqualConstraint(0); public static NaNConstraint NaN => new NaNConstraint(); public static EmptyConstraint Empty => new EmptyConstraint(); public static UniqueItemsConstraint Unique => new UniqueItemsConstraint(); public static BinarySerializableConstraint BinarySerializable => new BinarySerializableConstraint(); public static XmlSerializableConstraint XmlSerializable => new XmlSerializableConstraint(); public static CollectionOrderedConstraint Ordered => new CollectionOrderedConstraint(); public static EqualConstraint EqualTo(object expected) { return new EqualConstraint(expected); } public static SameAsConstraint SameAs(object expected) { return new SameAsConstraint(expected); } public static GreaterThanConstraint GreaterThan(object expected) { return new GreaterThanConstraint(expected); } public static GreaterThanOrEqualConstraint GreaterThanOrEqualTo(object expected) { return new GreaterThanOrEqualConstraint(expected); } public static GreaterThanOrEqualConstraint AtLeast(object expected) { return new GreaterThanOrEqualConstraint(expected); } public static LessThanConstraint LessThan(object expected) { return new LessThanConstraint(expected); } public static LessThanOrEqualConstraint LessThanOrEqualTo(object expected) { return new LessThanOrEqualConstraint(expected); } public static LessThanOrEqualConstraint AtMost(object expected) { return new LessThanOrEqualConstraint(expected); } public static ExactTypeConstraint TypeOf(Type expectedType) { return new ExactTypeConstraint(expectedType); } public static ExactTypeConstraint TypeOf<TExpected>() { return new ExactTypeConstraint(typeof(TExpected)); } public static InstanceOfTypeConstraint InstanceOf(Type expectedType) { return new InstanceOfTypeConstraint(expectedType); } public static InstanceOfTypeConstraint InstanceOf<TExpected>() { return new InstanceOfTypeConstraint(typeof(TExpected)); } public static AssignableFromConstraint AssignableFrom(Type expectedType) { return new AssignableFromConstraint(expectedType); } public static AssignableFromConstraint AssignableFrom<TExpected>() { return new AssignableFromConstraint(typeof(TExpected)); } public static AssignableToConstraint AssignableTo(Type expectedType) { return new AssignableToConstraint(expectedType); } public static AssignableToConstraint AssignableTo<TExpected>() { return new AssignableToConstraint(typeof(TExpected)); } public static CollectionEquivalentConstraint EquivalentTo(IEnumerable expected) { return new CollectionEquivalentConstraint(expected); } public static CollectionSubsetConstraint SubsetOf(IEnumerable expected) { return new CollectionSubsetConstraint(expected); } public static CollectionSupersetConstraint SupersetOf(IEnumerable expected) { return new CollectionSupersetConstraint(expected); } [Obsolete("Deprecated, use Does.Contain")] public static SubstringConstraint StringContaining(string expected) { return new SubstringConstraint(expected); } [Obsolete("Deprecated, use Does.StartWith")] public static StartsWithConstraint StringStarting(string expected) { return new StartsWithConstraint(expected); } [Obsolete("Deprecated, use Does.EndWith")] public static EndsWithConstraint StringEnding(string expected) { return new EndsWithConstraint(expected); } [Obsolete("Deprecated, use Does.Match")] public static RegexConstraint StringMatching(string pattern) { return new RegexConstraint(pattern); } public static SamePathConstraint SamePath(string expected) { return new SamePathConstraint(expected); } public static SubPathConstraint SubPathOf(string expected) { return new SubPathConstraint(expected); } public static SamePathOrUnderConstraint SamePathOrUnder(string expected) { return new SamePathOrUnderConstraint(expected); } public static RangeConstraint InRange(IComparable from, IComparable to) { return new RangeConstraint(from, to); } } }