<PackageReference Include="NUnit" Version="4.3.1" />

EqualConstraint

public class EqualConstraint : Constraint
EqualConstraint is able to compare an actual value with the expected value provided in its constructor. Two objects are considered equal if both are null, or if both have the same value. NUnit has special semantics for some object types.
using NUnit.Framework.Internal; using System; using System.IO; using System.Runtime.CompilerServices; using NUnit.Framework.Internal; using System; using System.IO; using System.Linq; using System.Runtime.CompilerServices; namespace NUnit.Framework.Constraints { [NullableContext(1)] [Nullable(0)] public class EmptyDirectoryConstraint : Constraint { public override string Description => "an empty directory"; public override ConstraintResult ApplyTo<[Nullable(2)] TActual>(TActual actual) { DirectoryInfo directoryInfo = ConstraintUtils.RequireActual<DirectoryInfo>(actual, "actual", false); DirectoryInfo directoryInfo; bool isSuccess = !directoryInfo.EnumerateFileSystemInfos().Any(); bool isSuccess; return new ConstraintResult(this, actual, isSuccess); } public EmptyDirectoryConstraint() : base(Array.Empty<object>()) { } } }