XMLDocument: Add a test for SR-10776.

Author: YOCKOW

TestFoundation/TestXMLDocument.swift

@@ -39,6 +39,7 @@ class TestXMLDocument : LoopbackServerTest {
             ("test_optionPreserveAll", test_optionPreserveAll),
             ("test_rootElementRetainsDocument", test_rootElementRetainsDocument),
             ("test_nodeKinds", test_nodeKinds),
+            ("test_sr10776_documentName", test_sr10776_documentName),
         ]
     }
 
@@ -551,7 +552,7 @@ class TestXMLDocument : LoopbackServerTest {
 
         XCTAssertEqual(try? test(), "plans")
     }
-    
+
     func test_nodeKinds() {
         XCTAssertEqual(XMLDocument(rootElement: nil).kind, .document)
         XCTAssertEqual(XMLElement(name: "prefix:localName").kind, .element)
@@ -565,6 +566,13 @@ class TestXMLDocument : LoopbackServerTest {
         XCTAssertEqual(XMLDTDNode(xmlString: "<!ATTLIST A B CDATA #IMPLIED>")?.kind, .attributeDeclaration)
         XCTAssertEqual(XMLDTDNode(xmlString: "<!ELEMENT E EMPTY>")?.kind, .elementDeclaration)
         XCTAssertEqual(XMLDTDNode(xmlString: #"<!NOTATION f SYSTEM "F">"#)?.kind, .notationDeclaration)
+
+    func test_sr10776_documentName() {
+        let doc = XMLDocument(rootElement: nil)
+        XCTAssertNil(doc.name)
+        
+        doc.name = "name"
+        XCTAssertNil(doc.name) // `name` of XMLDocument is always nil.
     }
 }