Add support for projecting method groups

src/EntityFrameworkCore.Projectables/Services/ProjectableExpressionReplacer.cs

@@ -41,6 +41,20 @@ bool TryGetReflectedExpression(MemberInfo memberInfo, [NotNullWhen(true)] out La
 
         protected override Expression VisitMethodCall(MethodCallExpression node)
         {
+            // Replace MethodGroup arguments with their reflected expressions.
+            // Note that MethodCallExpression.Update returns the original Expression if argument values have not changed.
+            node = node.Update(node.Object, node.Arguments.Select(arg => arg switch {
+                UnaryExpression {
+                    NodeType: ExpressionType.Convert,
+                    Operand: MethodCallExpression {
+                        NodeType: ExpressionType.Call,
+                        Method: { Name: nameof(MethodInfo.CreateDelegate), DeclaringType.Name: nameof(MethodInfo) },
+                        Object: ConstantExpression { Value: MethodInfo methodInfo }
+                    }
+                } => TryGetReflectedExpression(methodInfo, out var expressionArg) ? expressionArg : arg,
+                _ => arg
+            }));
+
             // Get the overriding methodInfo based on te type of the received of this expression
             var methodInfo = node.Object?.Type.GetConcreteMethod(node.Method) ?? node.Method;
 

tests/EntityFrameworkCore.Projectables.FunctionalTests/MethodGroupTests.ProjectOverMethodGroup.verified.txt

@@ -0,0 +1,4 @@
+SELECT [e].[Id], [e0].[Id] + 1, [e0].[Id]
+FROM [Entity] AS [e]
+LEFT JOIN [Entity] AS [e0] ON [e].[Id] = [e0].[EntityId]
+ORDER BY [e].[Id]

tests/EntityFrameworkCore.Projectables.FunctionalTests/MethodGroupTests.cs

@@ -0,0 +1,34 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using EntityFrameworkCore.Projectables.FunctionalTests.Helpers;
+using Microsoft.EntityFrameworkCore;
+using VerifyXunit;
+using Xunit;
+
+namespace EntityFrameworkCore.Projectables.FunctionalTests;
+
+[UsesVerify]
+public class MethodGroupTests
+{
+    public record Entity
+    {
+        public int Id { get; set; }
+
+        public List<Entity>? RelatedEntities { get; set; }
+    }
+
+    [Projectable]
+    public static int NextId(Entity entity) => entity.Id + 1;
+
+    [Fact]
+    public Task ProjectOverMethodGroup()
+    {
+        using var dbContext = new SampleDbContext<Entity>();
+
+        var query = dbContext.Set<Entity>()
+            .Select(x => new { NextIds = x.RelatedEntities!.Select(NextId) });
+
+        return Verifier.Verify(query.ToQueryString());
+    }
+}