Add extra unittests for NullPropagation / ToString / AllowEqualsAndTo…

…StringMethodsOnObject is true

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

@@ -328,7 +328,7 @@ public bool TryGenerateAndAlsoNotNullExpression(Expression sourceExpression, boo
     {
         var expressions = CollectExpressions(addSelf, sourceExpression);
 
-        if (expressions.Count == 1 && !(expressions[0] is MethodCallExpression))
+        if (expressions.Count == 1 && expressions[0] is not MethodCallExpression)
         {
             generatedExpression = sourceExpression;
             return false;

test/System.Linq.Dynamic.Core.Tests/Parser/ExpressionParserTests.cs

@@ -390,8 +390,7 @@ public void Parse_When_PrioritizePropertyOrFieldOverTheType_IsTrue(string expres
             CustomTypeProvider = _dynamicTypeProviderMock.Object,
             AllowEqualsAndToStringMethodsOnObject = true
         };
-        ParameterExpression[] parameters = [ParameterExpressionHelper.CreateParameterExpression(typeof(Company), "company")
-        ];
+        ParameterExpression[] parameters = [ ParameterExpressionHelper.CreateParameterExpression(typeof(Company), "company") ];
         var sut = new ExpressionParser(parameters, expression, null, config);
 
         // Act

test/System.Linq.Dynamic.Core.Tests/QueryableTests.Where.cs

@@ -389,6 +389,58 @@ public void Where_Dynamic_CompareObjectToInt_ConvertObjectToSupportComparisonIsF
         act.Should().Throw<InvalidOperationException>().And.Message.Should().MatchRegex("The binary operator .* is not defined for the types");
     }
 
+    [Fact]
+    public void Where_Dynamic_NullPropagation_Test1_On_NullableDoubleToString_When_AllowEqualsAndToStringMethodsOnObject_True()
+    {
+        // Arrange
+        var config = new ParsingConfig
+        {
+            AllowEqualsAndToStringMethodsOnObject = true
+        };
+        var queryable = new[]
+        {
+            new { id = "1", d = (double?) null },
+            new { id = "2", d = (double?) 5 },
+            new { id = "3", d = (double?) 50 },
+            new { id = "4", d = (double?) 40 }
+        }.AsQueryable();
+
+        // Act
+        var result = queryable
+            .Where(config, """np(it.d, 0).ToString().StartsWith("5", StringComparison.OrdinalIgnoreCase)""")
+            .Select<double?>("d")
+            .ToArray();
+
+        // Assert
+        result.Should().ContainInConsecutiveOrder(5, 50);
+    }
+
+    [Fact]
+    public void Where_Dynamic_NullPropagation_Test2_On_NullableDoubleToString_When_AllowEqualsAndToStringMethodsOnObject_True()
+    {
+        // Arrange
+        var config = new ParsingConfig
+        {
+            AllowEqualsAndToStringMethodsOnObject = true
+        };
+        var queryable = new[]
+        {
+            new { id = "1", d = (double?) null },
+            new { id = "2", d = (double?) 5 },
+            new { id = "3", d = (double?) 50 },
+            new { id = "4", d = (double?) 40 }
+        }.AsQueryable();
+
+        // Act
+        var result = queryable
+            .Where(config, """np(it.d.ToString(), "").StartsWith("5", StringComparison.OrdinalIgnoreCase)""")
+            .Select<double?>("d")
+            .ToArray();
+
+        // Assert
+        result.Should().ContainInConsecutiveOrder(5, 50);
+    }
+
     [ExcludeFromCodeCoverage]
     private class PersonWithObject
     {