Fix Query.Clone() shallow copy of Includes and Variables

- Add Clone() method to Include class for deep copying
- Fix Query.Clone() to deep-copy Includes list and Variables dictionary
- Fix XQuery.Clone() with same deep-copy fixes
- Add unit tests for the clone bug (independent list, objects, dict, properties)

Fixes #747

Agent-Logs-Url: https://github.com/sqlkata/querybuilder/sessions/d82ad628-73f5-4c2f-b56e-f4021ce1519f

Co-authored-by: ahmad-moussawi <2517523+ahmad-moussawi@users.noreply.github.com>

Author: Copilot

QueryBuilder.Tests/GeneralTests.cs

@@ -601,5 +601,70 @@ public void Passing_Negative_Boolean_False_To_Where_Should_Call_WhereTrue_Or_Whe
 
             Assert.Equal("SELECT * FROM [Table] WHERE [Col] != cast(0 as bit)", c[EngineCodes.SqlServer].ToString());
         }
+
+        [Fact]
+        public void Clone_ShouldProduceIndependentIncludesList()
+        {
+            var query = new Query("users")
+                .Include("posts", new Query("posts"), "user_id", "id");
+
+            var clone = query.Clone();
+
+            // Adding an include to the clone should not affect the original
+            clone.Include("comments", new Query("comments"), "user_id", "id");
+
+            Assert.Single(query.Includes);
+            Assert.Equal(2, clone.Includes.Count);
+        }
+
+        [Fact]
+        public void Clone_ShouldProduceIndependentIncludeObjects()
+        {
+            var query = new Query("users")
+                .Include("posts", new Query("posts"), "user_id", "id");
+
+            var clone = query.Clone();
+
+            // Modifying an include property on the clone should not affect the original
+            clone.Includes[0].Name = "modified_name";
+
+            Assert.Equal("posts", query.Includes[0].Name);
+            Assert.Equal("modified_name", clone.Includes[0].Name);
+        }
+
+        [Fact]
+        public void Clone_ShouldProduceIndependentVariablesDictionary()
+        {
+            var query = new Query("users").Define("limit", 10);
+
+            var clone = query.Clone();
+
+            // Adding a variable to the clone should not affect the original
+            clone.Define("offset", 5);
+
+            Assert.False(query.Variables.ContainsKey("offset"));
+            Assert.True(clone.Variables.ContainsKey("offset"));
+        }
+
+        [Fact]
+        public void Clone_ShouldPreserveAllProperties()
+        {
+            var query = new Query("users")
+                .Select("id", "name")
+                .Where("active", true)
+                .Distinct()
+                .As("u")
+                .Include("posts", new Query("posts"), "user_id", "id")
+                .Define("myvar", 42);
+
+            var clone = query.Clone();
+
+            Assert.Equal(query.QueryAlias, clone.QueryAlias);
+            Assert.Equal(query.IsDistinct, clone.IsDistinct);
+            Assert.Equal(query.Method, clone.Method);
+            Assert.Equal(query.Includes.Count, clone.Includes.Count);
+            Assert.Equal(query.Includes[0].Name, clone.Includes[0].Name);
+            Assert.Equal(query.Variables["myvar"], clone.Variables["myvar"]);
+        }
     }
 }

QueryBuilder/Include.cs

@@ -7,5 +7,17 @@ public class Include
         public string ForeignKey { get; set; }
         public string LocalKey { get; set; }
         public bool IsMany { get; set; }
+
+        public Include Clone()
+        {
+            return new Include
+            {
+                Name = Name,
+                Query = Query.Clone(),
+                ForeignKey = ForeignKey,
+                LocalKey = LocalKey,
+                IsMany = IsMany,
+            };
+        }
     }
 }

QueryBuilder/Query.cs

@@ -55,8 +55,8 @@ public override Query Clone()
             clone.QueryAlias = QueryAlias;
             clone.IsDistinct = IsDistinct;
             clone.Method = Method;
-            clone.Includes = Includes;
-            clone.Variables = Variables;
+            clone.Includes = Includes.Select(i => i.Clone()).ToList();
+            clone.Variables = new Dictionary<string, object>(Variables);
             return clone;
         }
 

SqlKata.Execution/XQuery.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Data;
 using System.Linq;
 using SqlKata.Compilers;
@@ -35,8 +36,8 @@ public override Query Clone()
             query.QueryAlias = QueryAlias;
             query.IsDistinct = IsDistinct;
             query.Method = Method;
-            query.Includes = Includes;
-            query.Variables = Variables;
+            query.Includes = Includes.Select(i => i.Clone()).ToList();
+            query.Variables = new Dictionary<string, object>(Variables);
 
             query.SetEngineScope(EngineScope);