Fix #432 ?

Author: StefH

src/System.Linq.Dynamic.Core/Parser/ExpressionHelper.cs

@@ -323,8 +323,7 @@ private List<Expression> CollectExpressions(bool addSelf, Expression sourceExpre
                         break;
 
                     case MethodCallExpression methodCallExpression:
-                        // FIX method without parameter: https://github.com/zzzprojects/System.Linq.Dynamic.Core/issues/432
-                        expression = methodCallExpression.Arguments.FirstOrDefault();
+                        expression = methodCallExpression.Object;
                         expressionRecognized = true;
                         break;
 

test/System.Linq.Dynamic.Core.Tests/ExpressionTests.cs

@@ -1,4 +1,5 @@
-using Newtonsoft.Json.Linq;
+using FluentAssertions;
+using Newtonsoft.Json.Linq;
 using NFluent;
 using System.Collections.Generic;
 using System.Dynamic;
@@ -49,6 +50,17 @@ public class TestObjectIdClass
             public long ObjectId { get; set; }
         }
 
+        public class Foo
+        {
+            public Foo FooValue { get; set; }
+
+            public string Zero() => null;
+
+            public string One(int x) => null;
+
+            public string Two(int x, int y) => null;
+        }
+
         [Fact]
         public void ExpressionTests_Add_Number()
         {
@@ -1394,6 +1406,72 @@ public void ExpressionTests_NullPropagating(string test, string query)
             Check.That(queryAsString).Equals(query);
         }
 
+        [Fact]
+        public void ExpressionTests_NullPropagating_InstanceMethod_Zero_Arguments()
+        {
+            // Arrange 1
+            var expression = "np(FooValue.Zero().Length)";
+
+            // Act 1
+            var lambdaExpression = DynamicExpressionParser.ParseLambda(typeof(Foo), null, expression, new Foo());
+
+            // Assert 1
+            lambdaExpression.ToString().Should().Be("Param_0 => IIF((((Param_0 != null) AndAlso (Param_0.FooValue != null)) AndAlso (Param_0.FooValue.Zero() != null)), Convert(Param_0.FooValue.Zero().Length), null)");
+
+            // Arrange 2
+            var q = new[] { new Foo { FooValue = new Foo() } }.AsQueryable();
+
+            // Act 2
+            var result = q.Select(expression).FirstOrDefault() as string;
+
+            // Assert 2
+            result.Should().BeNull();
+        }
+
+        [Fact]
+        public void ExpressionTests_NullPropagating_InstanceMethod_One_Argument()
+        {
+            // Arrange 1
+            var expression = "np(FooValue.One(1).Length)";
+
+            // Act 1
+            var lambdaExpression = DynamicExpressionParser.ParseLambda(typeof(Foo), null, expression, new Foo());
+
+            // Assert 1
+            lambdaExpression.ToString().Should().Be("Param_0 => IIF((((Param_0 != null) AndAlso (Param_0.FooValue != null)) AndAlso (Param_0.FooValue.One(1) != null)), Convert(Param_0.FooValue.One(1).Length), null)");
+
+            // Arrange 2
+            var q = new[] { new Foo { FooValue = new Foo() } }.AsQueryable();
+
+            // Act 2
+            var result = q.Select(expression).FirstOrDefault() as string;
+
+            // Assert 2
+            result.Should().BeNull();
+        }
+
+        [Fact]
+        public void ExpressionTests_NullPropagating_InstanceMethod_Two_Arguments()
+        {
+            // Arrange 1
+            var expression = "np(FooValue.Two(1, 42).Length)";
+
+            // Act 1
+            var lambdaExpression = DynamicExpressionParser.ParseLambda(typeof(Foo), null, expression, new Foo());
+
+            // Assert 1
+            lambdaExpression.ToString().Should().Be("Param_0 => IIF((((Param_0 != null) AndAlso (Param_0.FooValue != null)) AndAlso (Param_0.FooValue.Two(1, 42) != null)), Convert(Param_0.FooValue.Two(1, 42).Length), null)");
+
+            // Arrange 2
+            var q = new[] { new Foo { FooValue = new Foo() } }.AsQueryable();
+
+            // Act 2
+            var result = q.Select(expression).FirstOrDefault() as string;
+
+            // Assert 2
+            result.Should().BeNull();
+        }
+
         [Fact]
         public void ExpressionTests_NullPropagation_Method()
         {

test/System.Linq.Dynamic.Core.Tests/System.Linq.Dynamic.Core.Tests.csproj

@@ -37,6 +37,7 @@
         <PackageReference Include="xunit" Version="2.4.1" />
         <PackageReference Include="NFluent" Version="2.7.0" />
         <PackageReference Include="Moq" Version="4.13.1" />
+        <!--<PackageReference Include="ExpressionTreeToString" Version="3.1.47" />-->
     </ItemGroup>
 
     <ItemGroup Condition=" '$(TargetFramework)' == 'net452' ">