<PackageReference Include="NUnit" Version="4.3.2" />

NUnit.Framework.Constraints.StringConstraint

public abstract class StringConstraint : Constraint
StringConstraint is the abstract base for constraints that operate on strings. It supports the IgnoreCase modifier for string operations.
namespace NUnit.Framework.Constraints { public abstract class StringConstraint : Constraint { protected readonly string expected; protected bool caseInsensitive; protected string descriptionText; public virtual StringConstraint IgnoreCase { get; } protected StringConstraint(); protected StringConstraint(string expected); protected abstract bool Matches(string actual); } }