draft of a fix for MindboxExpressionStringBuilder

Mindbox.Expressions.Tests/ExpandExpressionTests.cs

@@ -15,13 +15,55 @@ namespace Mindbox.Expressions.Tests
 	[TestClass]
 	public class ExpandExpressionTests
 	{
+		public interface ITest
+		{
+			int Value { get; }
+		}
+
+		public class A : ITest
+		{
+			public int Value { get; set; }
+		}
+
+		public class B : ITest
+		{
+			public int Value { get; set; }
+		}
+
 		[TestInitialize]
 		public void Initialize()
 		{
 			ExpressionsConfiguration.ExpressionEvaluatorFactory =
-				() => InterpretingExpressionEvaluator.Instance;
+				() => CachingCompilingExpressionEvaluator.Instance;
 		}
 
+		private Expression<Func<TTestInterface, int>> 
+			GetSimleFExpression<TTestInterface>()
+			where TTestInterface : ITest
+		{
+			Expression<Func<TTestInterface, int>> f1 = x => x.Value;
+			return f1;
+		}
+
+		private Expression<Func<TTestInterface, Expression<Func<TTestInterface, int>>>> 
+			GetFExpression<TTestInterface>()
+			where TTestInterface : ITest, new()
+		{
+			Expression<Func<TTestInterface, Expression<Func<TTestInterface, int>>>> f1 = x => y => 
+				x.Value + y.Value;
+			return f1;
+		}
+
+		[TestMethod]
+		public void ExpandWithGenericParameters()
+		{
+			Expression<Func<A, int>> f2 = x => GetFExpression<A>().Evaluate(x).Evaluate(x);
+			Expression<Func<B, int>> f3 = x => GetFExpression<B>().Evaluate(x).Evaluate(x);
+
+			var result1 = f2.ExpandExpressions();
+			var result2 = f3.ExpandExpressions();
+		}
+
 		[TestMethod]
 		public void ExpandExpressionsSimpleTest()
 		{

Mindbox.Expressions/Evaluators/Caching/MindboxExpressionStringBuilder.cs

@@ -565,6 +565,24 @@ protected override Expression VisitMethodCall(MethodCallExpression node)
 				Out(".");
 			}
 			Out(node.Method.Name);
+
+			if (node.Method.IsGenericMethod)
+			{
+				Out("<");
+				var isFirst = true;
+				foreach (var genericArgument in node.Method.GetGenericArguments())
+				{
+					if (!isFirst)
+					{
+						Out(",");
+					}
+					isFirst = false;
+
+					Out(genericArgument.ToString());
+				}
+				Out(">");
+			}
+
 			Out("(");
 			for (int i = start, n = node.Arguments.Count; i < n; i++)
 			{