OperatorOverloadingFixture.cs

using System;
using System.Reflection;
using NHibernate.Criterion;
using NUnit.Framework;

namespace NHibernate.Test.ExpressionTest
{
	[TestFixture]
	public class OperatorOverloadingFixture
	{
		[Test]
		public void CanUseAndOperatorForExpressions()
		{
			AbstractCriterion lhs = Expression.Eq("foo", "bar");
			AbstractCriterion rhs = Expression.Gt("date", DateTime.Today);

			AbstractCriterion and = lhs && rhs;

			Assert.AreEqual(typeof(AndExpression), and.GetType());
			Assert.AreEqual(lhs, GetLeftSide(and));
			Assert.AreEqual(rhs, GetRightSide(and));
		}

		[Test]
		public void CanUseOrOperatorForEpressions()
		{
			AbstractCriterion lhs = Expression.Eq("foo", "bar");
			AbstractCriterion rhs = Expression.Gt("date", DateTime.Today);

			AbstractCriterion or = lhs || rhs;

			Assert.AreEqual(typeof(OrExpression), or.GetType());
			Assert.AreEqual(lhs, GetLeftSide(or));
			Assert.AreEqual(rhs, GetRightSide(or));
		}

		[Test]
		public void CanUseNotOperatorForExpressions()
		{
			AbstractCriterion lhs = Expression.Eq("foo", "bar");
			AbstractCriterion not = !lhs;

			Assert.AreEqual(typeof(NotExpression), not.GetType());
			AbstractCriterion not_value = (AbstractCriterion) GetField("_criterion", typeof(NotExpression)).GetValue(not);
			Assert.AreEqual(lhs, not_value);
		}

		private static AbstractCriterion GetLeftSide(AbstractCriterion criterion)
		{
			return (AbstractCriterion) GetField("_lhs", typeof(LogicalExpression)).GetValue(criterion);
		}

		private static FieldInfo GetField(string lhs, System.Type type)
		{
			return type.GetField(lhs, BindingFlags.Instance | BindingFlags.NonPublic);
		}

		private static AbstractCriterion GetRightSide(AbstractCriterion criterion)
		{
			return (AbstractCriterion) GetField("_rhs", typeof(LogicalExpression)).GetValue(criterion);
		}
	}
}