Merge pull request #4 from LiveUI/singletonList

Fix to handle singleton lists with ListDecodingStrategy.

Sources/XMLCoding/Decoder/XMLUnkeyedDecodingContainer.swift

@@ -37,8 +37,16 @@ internal struct _XMLUnkeyedDecodingContainer : UnkeyedDecodingContainer {
         case .collapseListUsingItemTag(let itemTag):
             if container.count == 1,
                 let itemKeyMap = container[0] as? [AnyHashable: Any],
-                let list = itemKeyMap[itemTag] as? [Any] {
-                    self.container = list
+                let entry = itemKeyMap[itemTag] {
+                    // if there are multiple items in the list,
+                    // the entry will be a list
+                    if let list = entry as? [Any] {
+                        self.container = list
+                    } else {
+                        // otherwise it will be the singleton entry;
+                        // place it in a list for the container
+                        self.container = [entry]
+                    }
             } else {
                 self.container = []
             }

Tests/XMLCodingTests/XMLParsingTests.swift

@@ -18,6 +18,17 @@ let LIST_XML = """
     </Response>
     """
 
+let SINGLETON_LIST_XML = """
+    <Response>
+        <Result />
+        <MetadataList>
+            <item>
+                <Id>id1</Id>
+            </item>
+        </MetadataList>
+    </Response>
+    """
+
 class XMLParsingTests: XCTestCase {
     struct Result: Codable {
         let message: String?
@@ -130,6 +141,22 @@ class XMLParsingTests: XCTestCase {
         XCTAssertEqual(LIST_XML, encodedString)
     }
 
+    func testSingletonListDecodingWithDefaultStrategy() throws {
+        guard let inputData = SINGLETON_LIST_XML.data(using: .utf8) else {
+            return XCTFail()
+        }
+
+        let response = try XMLDecoder().decode(ResponseWithList.self, from: inputData)
+
+        XCTAssertEqual(1, response.metadataList.items.count)
+
+        // encode the output to make sure we get what we started with
+        let data = try XMLEncoder().encode(response, withRootKey: "Response")
+        let encodedString = String(data: data, encoding: .utf8) ?? ""
+
+        XCTAssertEqual(SINGLETON_LIST_XML, encodedString)
+    }
+
     func testListDecodingWithCollapseItemTagStrategy() throws {
         guard let inputData = LIST_XML.data(using: .utf8) else {
             return XCTFail()
@@ -150,11 +177,33 @@ class XMLParsingTests: XCTestCase {
 
         XCTAssertEqual(LIST_XML, encodedString)
     }
+
+    func testSingletonListDecodingWithCollapseItemTagStrategy() throws {
+        guard let inputData = SINGLETON_LIST_XML.data(using: .utf8) else {
+            return XCTFail()
+        }
+
+        let decoder = XMLDecoder()
+        decoder.listDecodingStrategy = .collapseListUsingItemTag("item")
+        let response = try decoder.decode(ResponseWithCollapsedList.self, from: inputData)
+
+        XCTAssertEqual(1, response.metadataList.count)
+
+        let encoder = XMLEncoder()
+        encoder.listEncodingStrategy = .expandListWithItemTag("item")
+
+        // encode the output to make sure we get what we started with
+        let data = try encoder.encode(response, withRootKey: "Response")
+        let encodedString = String(data: data, encoding: .utf8) ?? ""
+
+        XCTAssertEqual(SINGLETON_LIST_XML, encodedString)
+    }
 
     static var allTests = [
         ("testEmptyElement", testEmptyElement),
         ("testEmptyElementNotEffectingPreviousElement", testEmptyElementNotEffectingPreviousElement),
         ("testListDecodingWithDefaultStrategy", testListDecodingWithDefaultStrategy),
+        ("testSingletonListDecodingWithDefaultStrategy", testSingletonListDecodingWithDefaultStrategy),
         ("testListDecodingWithCollapseItemTagStrategy", testListDecodingWithCollapseItemTagStrategy)
     ]
 }