mono/mcs/class/System.Core/Test/System.Linq.Expressions/ExpressionTest_Lambda.cs

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//
// Authors:
//   Miguel de Icaza ([email protected])

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 ());
		}
	}
}