using System;

namespace NUnit.Framework
{
	/// <summary>
	/// Class to assert that the actual value is greater than the expected value.
	/// </summary>
	public class LessAsserter : ComparisonAsserter
	{
		/// <summary>
		/// Constructs a GreaterAsserter for two objects implementing IComparable
		/// </summary>
		/// <param name="expected">The expected value</param>
		/// <param name="actual">The actual value</param>
		/// <param name="message">The message to issue on failure</param>
		/// <param name="args">Arguments to apply in formatting the message</param>
		public LessAsserter( IComparable expected, IComparable actual, string message, params object[] args )
			: base( expected, actual, message, args ) { }

		/// <summary>
		/// Test whether the actual is greater than the expected, building up
		/// the failure message for later use if they are not.
		/// </summary>
		/// <returns>True if actual is greater than expected</returns>
		public override bool Test()
		{
			if ( ((IComparable)actual).CompareTo(expected) < 0 ) return true;

			DisplayDifferences();
			return false;
		}

		private void DisplayDifferences()
		{
			FailureMessage.AddExpectedLine( string.Format( "Value less than {0}", expected ) );
			FailureMessage.AddActualLine(actual.ToString());
		}
	}
}