Add negative test-case to Correctness/ExpressionTrees.cs

ICSharpCode.Decompiler.Tests/TestCases/Correctness/ExpressionTrees.cs

@@ -12,24 +12,22 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Correctness
 		static void Main()
 		{
 			Test();
+			var twice = GetExpression(Expression.Constant(2)).Compile();
+			Console.WriteLine(twice(21));
 		}
 
-		public Expression<Func<int, int>> GetExpression(int i)
-		{
-			return a => a + i;
-		}
-
-		public Expression<Func<int, Func<int, int>>> GetExpression2()
-		{
-			return a => b => a + b;
-		}
-
-		public static void Test()
+		static void Test()
 		{
 			int i = 0;
 			Expression<Func<int>> expression = () => i;
 			i = 1;
 			Console.WriteLine(expression.Compile()());
 		}
+
+		static Expression<Func<int, int>> GetExpression(Expression factor)
+		{
+			ParameterExpression parameterExpression = Expression.Parameter(typeof(int), "x");
+			return Expression.Lambda<Func<int, int>>(Expression.Multiply(parameterExpression, factor), parameterExpression);
+		}
 	}
 }