Encode element with empty key, empty element, and attributes (#223)

Fixes an edge case with intrinsic value key encoding.

Author: wooj2

Sources/XMLCoder/Auxiliaries/XMLCoderElement.swift

@@ -217,9 +217,16 @@ struct XMLCoderElement: Equatable {
         _ string: inout String,
         _ charactersEscapedInAttributes: [(String, String)]
     ) {
+        let attributesBelongingToContainer = self.elements.filter {
+            $0.key.isEmpty && !$0.attributes.isEmpty
+        }.flatMap {
+            $0.attributes
+        }
+        let allAttributes = self.attributes + attributesBelongingToContainer
+
         let attributes = formatting.contains(.sortedKeys) ?
-            self.attributes.sorted(by: { $0.key < $1.key }) :
-            self.attributes
+            allAttributes.sorted(by: { $0.key < $1.key }) :
+            allAttributes
         formatXMLAttributes(
             from: attributes,
             into: &string,
@@ -266,10 +273,9 @@ struct XMLCoderElement: Equatable {
 
         if !key.isEmpty {
             string += "<\(key)"
+            formatXMLAttributes(formatting, &string, escapedCharacters.attributes)
         }
 
-        formatXMLAttributes(formatting, &string, escapedCharacters.attributes)
-
         if !elements.isEmpty {
             let prettyPrintElements = prettyPrinted && !containsTextNodes
             if !key.isEmpty {
@@ -282,7 +288,9 @@ struct XMLCoderElement: Equatable {
                 string += "</\(key)>"
             }
         } else {
-            string += " />"
+            if !key.isEmpty {
+                string += " />"
+            }
         }
 
         return string

Tests/XMLCoderTests/Auxiliary/XMLElementTests.swift

@@ -64,4 +64,70 @@ class XMLElementTests: XCTestCase {
         XCTAssert(whitespaceElement2.isWhitespaceWithNoElements())
         XCTAssert(whitespaceElement3.isWhitespaceWithNoElements())
     }
+
+    func testNestedElementWith_Namespace_Attribute() {
+        typealias Attribute = XMLCoderElement.Attribute
+        typealias Element = XMLCoderElement
+        let nested = Element(key: "Nested",
+                             elements: [
+                                Element(key: "",
+                                        elements: [],
+                                        attributes: [
+                                            Attribute(key: "xsi:someName", value: "nestedAttrValue")
+                                        ]
+                                )],
+                             attributes: [
+                                Attribute(key: "xmlns:xsi", value: "https://example.com")
+                             ])
+        let inputNamespace = Attribute(key: "xmlns", value: "https://example.com")
+        let input = Element(key: "Input",
+                            elements: [nested],
+                            attributes: [inputNamespace])
+
+        let result = input.toXMLString(
+            escapedCharacters: (elements: XMLEncoder().charactersEscapedInElements,
+                                attributes: XMLEncoder().charactersEscapedInAttributes),
+            formatting: [],
+            indentation: .spaces(4)
+        )
+
+        XCTAssertEqual(result, """
+        <Input xmlns="https://example.com"><Nested xmlns:xsi="https://example.com" xsi:someName="nestedAttrValue"></Nested></Input>
+        """)
+    }
+    
+    func testNestedElementWith_Namespace_Attribute_Element() {
+        typealias Attribute = XMLCoderElement.Attribute
+        typealias Element = XMLCoderElement
+        let nested = Element(key: "Nested",
+                             elements: [
+                                Element(key: "",
+                                        elements: [
+                                            Element(key: "nonAttrField",
+                                                    elements: [Element(key: "", stringValue: "hello")],
+                                                    attributes: [])
+                                        ],
+                                        attributes: [
+                                            Attribute(key: "xsi:someName", value: "nestedAttrValue")
+                                        ]
+                                )],
+                             attributes: [
+                                Attribute(key: "xmlns:xsi", value: "https://example.com")
+                             ])
+        let inputNamespace = Attribute(key: "xmlns", value: "https://example.com")
+        let input = Element(key: "Input",
+                            elements: [nested],
+                            attributes: [inputNamespace])
+
+        let result = input.toXMLString(
+            escapedCharacters: (elements: XMLEncoder().charactersEscapedInElements,
+                                attributes: XMLEncoder().charactersEscapedInAttributes),
+            formatting: [],
+            indentation: .spaces(4)
+        )
+
+        XCTAssertEqual(result, """
+        <Input xmlns="https://example.com"><Nested xmlns:xsi="https://example.com" xsi:someName="nestedAttrValue"><nonAttrField>hello</nonAttrField></Nested></Input>
+        """)
+    }
 }