context: // Permission is hereby granted, free of charge, to any person obtaining
  // a copy of this software and associated documentation files (the
  // "Software"), to deal in the Software without restriction, including
  // without limitation the rights to use, copy, modify, merge, publish,
  // distribute, sublicense, and/or sell copies of the Software, and to
  // permit persons to whom the Software is furnished to do so, subject to
  // the following conditions:
  //
  // The above copyright notice and this permission notice shall be
  // included in all copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  //
  // Authors:
  //   Miguel de Icaza (miguel@novell.com)
  //   Jb Evain (jbevain@novell.com)
  //
  
  using System;
  using System.Reflection;
  using System.Linq;
  using System.Linq.Expressions;
  using NUnit.Framework;
  
  namespace MonoTests.System.Linq.Expressions
  {
  	[TestFixture]
  	public class ExpressionTest_Lambda
  	{
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void NonDelegateTypeInCtor ()
  		{
  			// The first parameter must be a delegate type
  			Expression.Lambda (typeof(string), Expression.Constant (1), new ParameterExpression [0]);
  		}
  
  		delegate object delegate_object_emtpy ();
  		delegate object delegate_object_int (int a);
  		delegate object delegate_object_string (string s);
  		delegate object delegate_object_object (object s);
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidConversion ()
  		{
  			// float to object, invalid
  			Expression.Lambda (typeof (delegate_object_emtpy), Expression.Constant (1.0), new ParameterExpression [0]);
  		}
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidConversion2 ()
  		{
  			// float to object, invalid
  			Expression.Lambda (typeof (delegate_object_emtpy), Expression.Constant (1), new ParameterExpression [0]);
  		}
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidArgCount ()
  		{
  			// missing a parameter
  			Expression.Lambda (typeof (delegate_object_int), Expression.Constant ("foo"), new ParameterExpression [0]);
  		}
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidArgCount2 ()
  		{
  			// extra parameter
  			ParameterExpression p = Expression.Parameter (typeof (int), "AAA");
  			Expression.Lambda (typeof (delegate_object_emtpy), Expression.Constant ("foo"), new ParameterExpression [1] {p});
  		}
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidArgType ()
  		{
  			// invalid argument type
  			ParameterExpression p = Expression.Parameter (typeof (string), "AAA");
  			Expression.Lambda (typeof (delegate_object_int), Expression.Constant ("foo"), new ParameterExpression [1] {p});
  		}
  
  		[Test]
  		[ExpectedException (typeof (ArgumentException))]
  		public void InvalidArgType2 ()
  		{
  			// invalid argument type
  
  			ParameterExpression p = Expression.Parameter (typeof (string), "AAA");
  			Expression.Lambda (typeof (delegate_object_object), Expression.Constant ("foo"), new ParameterExpression [1] {p});
  		}
  
  		[Test]
  		public void Assignability ()
  		{
  			// allowed: string to object
  			Expression.Lambda (typeof (delegate_object_emtpy), Expression.Constant ("string"), new ParameterExpression [0]);
  
  			// allowed delegate has string, delegate has base class (object)
  			ParameterExpression p = Expression.Parameter (typeof (object), "ParObject");
  			var l = Expression.Lambda (typeof (delegate_object_string), Expression.Constant (""), new ParameterExpression [1] {p});
  
  			Assert.AreEqual ("ParObject => \"\"", l.ToString ());
  		}
  
  		[Test]
  		[ExpectedException(typeof(InvalidOperationException))]
  		public void ParameterOutOfScope ()
  		{
  			ParameterExpression a = Expression.Parameter(typeof (int), "a");
  			ParameterExpression second_a = Expression.Parameter(typeof(int), "a");
  
  			// Here we have the same name for the parameter expression, but
  			// we pass a different object to the Lambda expression, so they are
  			// different, this should throw
  			Expression<Func<int,int>> l = Expression.Lambda<Func<int,int>>(a, new ParameterExpression [] { second_a });
  			l.Compile ();
  		}
  
  		[Test]
  		public void ParameterRefTest ()
  		{
  			ParameterExpression a = Expression.Parameter(typeof(int), "a");
  			ParameterExpression b = Expression.Parameter(typeof(int), "b");
  
  			Expression<Func<int,int,int>> l = Expression.Lambda<Func<int,int,int>>(
  				Expression.Add (a, b), new ParameterExpression [] { a, b });
  
  			Assert.AreEqual (typeof (Func<int, int, int>), l.Type);
  			Assert.AreEqual ("(a, b) => (a + b)", l.ToString ());
  
  			Func<int,int,int> xx = l.Compile ();
  			int res = xx (10, 20);
  			Assert.AreEqual (res, 30);
  		}
  
  		[Test]
  		public void Compile ()
  		{
  			Expression<Func<int>> l = Expression.Lambda<Func<int>> (Expression.Constant (1), new ParameterExpression [0]);
  			Assert.AreEqual (typeof (Func<int>), l.Type);
  			Assert.AreEqual ("() => 1", l.ToString ());
  
  			Func<int> fi = l.Compile ();
  			fi ();
  		}
  
  		[Test]
  		[ExpectedException(typeof(ArgumentException))]
  		public void ReturnValueCheck ()
  		{
  			ParameterExpression p1 = Expression.Parameter(typeof(int?), "va");
  			ParameterExpression p2 = Expression.Parameter(typeof(int?), "vb");
  			Expression add = Expression.Add(p1, p2);
  
  
  			// This should throw, since the add.Type is "int?" and the return
  			// type we have here is int.
  			Expression.Lambda<Func<int?,int?,int>> (add, p1, p2);
  		}
  
  		public static void Foo ()
  		{
  		}
  
  		[Test]
  		public void LambdaType ()
  		{
  			var l = Expression.Lambda (Expression.Constant (1), new [] { Expression.Parameter (typeof (int), "foo") });
  
  			Assert.AreEqual (typeof (Func<int, int>), l.Type);
  
  			l = Expression.Lambda (Expression.Call (null, GetType ().GetMethod ("Foo")), new [] { Expression.Parameter (typeof (string), "foofoo") });
  
  			Assert.AreEqual (typeof (Action<string>), l.Type);
  		}
  
  		[Test]
  		public void UnTypedLambdaReturnsExpressionOfDelegateType ()
  		{
  			var l = Expression.Lambda ("foo".ToConstant ());
  
  			Assert.AreEqual (typeof (Expression<Func<string>>), l.GetType ());
  		}
  
  		public static int CallDelegate (Func<int, int> e)
  		{
  			return e (42);
  		}
  
  		[Test]
  		public void LambdaPassedAsDelegate ()
  		{
  			var pi = Expression.Parameter (typeof (int), "i");
  			var identity = Expression.Lambda<Func<int, int>> (pi, pi);
  
  			var l = Expression.Lambda<Func<int>> (
  				Expression.Call (
  					GetType ().GetMethod ("CallDelegate"),
  					identity)).Compile ();
  
  			Assert.AreEqual (42, l ());
  		}
  
  		[Test]
  		[Category ("NotWorking")]
  		public void LambdaPassedAsDelegateUsingParentParameter ()
  		{
  			var a = Expression.Parameter (typeof (int), "a");
  			var b = Expression.Parameter (typeof (int), "b");
  
  			var l = Expression.Lambda<Func<int, int>> (
  				Expression.Call (
  					this.GetType ().GetMethod ("CallDelegate"),
  					Expression.Lambda<Func<int, int>> (
  							Expression.Multiply (a, b), b)),
  				a).Compile ();
  
  			Assert.AreEqual (84, l (2));
  		}
  
  		public static int CallFunc (Func<int, int> e, int i)
  		{
  
gt: 			return e (i);