// ****************************************************************
// Copyright 2007, Charlie Poole
// This is free software licensed under the NUnit license. You may
// obtain a copy of the license at http://nunit.org
// ****************************************************************

namespace NUnit.Framework.Constraints
{
    /// <summary>
    /// EmptyStringConstraint tests whether a string is empty.
    /// </summary>
    public class EmptyStringConstraint : Constraint
    {
        /// <summary>
        /// Test whether the constraint is satisfied by a given value
        /// </summary>
        /// <param name="actual">The value to be tested</param>
        /// <returns>True for success, false for failure</returns>
        public override bool Matches(object actual)
        {
            this.actual = actual;

            return actual as string == string.Empty;
        }

        /// <summary>
        /// Write the constraint description to a MessageWriter
        /// </summary>
        /// <param name="writer">The writer on which the description is displayed</param>
        public override void WriteDescriptionTo(MessageWriter writer)
        {
            writer.Write("<empty>");
        }
    }
}
