/src/NUnit/framework/Constraints/RangeConstraint.cs

// ****************************************************************

// Copyright 2008, Charlie Poole

// This is free software licensed under the NUnit license. You may

// obtain a copy of the license at http://nunit.org

// ****************************************************************



using System;

using System.Collections;

#if NET_2_0

using System.Collections.Generic;

#endif



namespace NUnit.Framework.Constraints

{

    /// <summary>

    /// RangeConstraint tests whethe two values are within a 

    /// specified range.

    /// </summary>

    public class RangeConstraint : Constraint

    {

        private IComparable from;

        private IComparable to;



        private ComparisonAdapter comparer = ComparisonAdapter.Default;



        /// <summary>

        /// Initializes a new instance of the <see cref="T:RangeConstraint"/> class.

        /// </summary>

        /// <param name="from">From.</param>

        /// <param name="to">To.</param>

        public RangeConstraint(IComparable from, IComparable to) : base( from, to )

        {

            this.from = from;

            this.to = to;

        }



        /// <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;



            if ( from == null || to == null || actual == null)

                throw new ArgumentException( "Cannot compare using a null reference", "expected" );



            return comparer.Compare(from, actual) <= 0 &&

                   comparer.Compare(to, actual) >= 0;

        }



        /// <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("in range ({0},{1})", from, to);

        }



        /// <summary>

        /// Modifies the constraint to use an IComparer and returns self.

        /// </summary>

        public RangeConstraint Using(IComparer comparer)

        {

            this.comparer = ComparisonAdapter.For(comparer);

            return this;

        }



#if NET_2_0

        /// <summary>

        /// Modifies the constraint to use an IComparer&lt;T&gt; and returns self.

        /// </summary>

        public RangeConstraint Using<T>(IComparer<T> comparer)

        {

            this.comparer = ComparisonAdapter.For(comparer);

            return this;

        }



        /// <summary>

        /// Modifies the constraint to use a Comparison&lt;T&gt; and returns self.

        /// </summary>

        public RangeConstraint Using<T>(Comparison<T> comparer)

        {

            this.comparer = ComparisonAdapter.For(comparer);

            return this;

        }

#endif

    }

}