Fix copy document with descendants onto self (#17661)

* Filter self out of descedants for self onto self copy

* Optimized code

---------

Co-authored-by: Bjarke Berg <mail@bergmania.dk>

src/Umbraco.Core/Services/ContentService.cs

@@ -2699,6 +2699,13 @@ public class ContentService : RepositoryService, IContentService
                         GetPagedDescendants(content.Id, page++, pageSize, out total);
                     foreach (IContent descendant in descendants)
                     {
+                        // when copying a branch into itself, the copy of a root would be seen as a descendant
+                        // and would be copied again => filter it out.
+                        if (descendant.Id == copy.Id)
+                        {
+                            continue;
+                        }
+
                         // if parent has not been copied, skip, else gets its copy id
                         if (idmap.TryGetValue(descendant.ParentId, out parentId) == false)
                         {

tests/Umbraco.Tests.Integration/Umbraco.Infrastructure/Services/ContentEditingServiceTests.Copy.cs

@@ -198,6 +198,48 @@ public partial class ContentEditingServiceTests
         }
     }
 
+    [TestCase(true)]
+    [TestCase(false)]
+    public async Task Can_Copy_Onto_Self(bool includeDescendants)
+    {
+        var contentType = await CreateTextPageContentTypeAsync();
+        (IContent root, IContent child) = await CreateRootAndChildAsync(contentType);
+
+        var result = await ContentEditingService.CopyAsync(root.Key, root.Key, false, includeDescendants, Constants.Security.SuperUserKey);
+        Assert.IsTrue(result.Success);
+        Assert.AreEqual(ContentEditingOperationStatus.Success, result.Status);
+
+        VerifyCopy(result.Result);
+
+        // re-get and re-test
+        VerifyCopy(await ContentEditingService.GetAsync(result.Result!.Key));
+
+        void VerifyCopy(IContent? copiedRoot)
+        {
+            Assert.IsNotNull(copiedRoot);
+            Assert.AreEqual(root.Id, copiedRoot.ParentId);
+            Assert.IsTrue(copiedRoot.HasIdentity);
+            Assert.AreNotEqual(root.Key, copiedRoot.Key);
+            Assert.AreEqual(root.Name, copiedRoot.Name);
+            var copiedChildren = ContentService.GetPagedChildren(copiedRoot.Id, 0, 100, out var total).ToArray();
+
+            if (includeDescendants)
+            {
+                Assert.AreEqual(1, copiedChildren.Length);
+                Assert.AreEqual(1, total);
+                var copiedChild = copiedChildren.First();
+                Assert.AreNotEqual(child.Id, copiedChild.Id);
+                Assert.AreNotEqual(child.Key, copiedChild.Key);
+                Assert.AreEqual(child.Name, copiedChild.Name);
+            }
+            else
+            {
+                Assert.AreEqual(0, copiedChildren.Length);
+                Assert.AreEqual(0, total);
+            }
+        }
+    }
+
     [Test]
     public async Task Can_Relate_Copy_To_Original()
     {