using System; using System.Collections; namespace NUnit.Framework.Constraints { public abstract class CollectionConstraint : Constraint { protected CollectionConstraint() { } protected CollectionConstraint(object arg) : base(arg) { } protected static bool IsEmpty(IEnumerable enumerable) { ICollection collection = enumerable as ICollection; if (collection != null) return collection.Count == 0; IEnumerator enumerator = enumerable.GetEnumerator(); try { if (enumerator.MoveNext()) { object current = enumerator.Current; return false; } } finally { IDisposable disposable = enumerator as IDisposable; if (disposable != null) disposable.Dispose(); } return true; } public override ConstraintResult ApplyTo<TActual>(TActual actual) { IEnumerable enumerable = actual as IEnumerable; if (enumerable == null) throw new ArgumentException("The actual value must be an IEnumerable", "actual"); return new ConstraintResult(this, actual, Matches(enumerable)); } protected abstract bool Matches(IEnumerable collection); } }