Back button and toggle button fixes (#237)

* Fixed a bug where an element's accessibility value could be omitted if it contained the .toggleButton trait but was not 0, 1 or 2.
* Fixed a bug where elements with both a .backButton trait and an accessibilityLabel equal to "back" weren't being deduplicated properly.

Author: RoyalPineapple

Example/Podfile.lock

@@ -1,9 +1,9 @@
 PODS:
-  - AccessibilitySnapshot/Core (0.7.0)
-  - AccessibilitySnapshot/iOSSnapshotTestCase (0.7.0):
+  - AccessibilitySnapshot/Core (0.8.0)
+  - AccessibilitySnapshot/iOSSnapshotTestCase (0.8.0):
     - AccessibilitySnapshot/Core
     - iOSSnapshotTestCase (~> 8.0)
-  - AccessibilitySnapshot/SnapshotTesting (0.7.0):
+  - AccessibilitySnapshot/SnapshotTesting (0.8.0):
     - AccessibilitySnapshot/Core
     - SnapshotTesting (~> 1.0)
   - iOSSnapshotTestCase (8.0.0):
@@ -32,7 +32,7 @@ EXTERNAL SOURCES:
     :path: "../AccessibilitySnapshot.podspec"
 
 SPEC CHECKSUMS:
-  AccessibilitySnapshot: a29652b9054223b6c2a19ef1c83631e2a62ecbf9
+  AccessibilitySnapshot: 9c1129f4d7653affc5f89f3086286bd50c11d5d4
   iOSSnapshotTestCase: a670511f9ee3829c2b9c23e6e68f315fd7b6790f
   Paralayout: 844978af530a061a31d849c7b554510190b9cddf
   SnapshotTesting: 8caa6661fea7c8019d5b46de77c16bab99c36c5c

Example/SnapshotTests/ReferenceImages/_64/SnapshotTests.AccessibilitySnapshotTests/[email protected]

@@ -13,6 +13,9 @@
 /* Description for the 'back button' accessibility trait */
 "trait.backbutton.description" = "Zurück Taste.";
 
+/* Descriptor for the 'back' portion of the 'back button' accessibility trait */
+"back.descriptor" = "Zurück";
+
 /* Description for the 'tab' accessibility trait */
 "trait.tab.description" = "Tabulator.";
 

Example/SnapshotTests/ReferenceImages/_64/SnapshotTests.AccessibilitySnapshotTests/[email protected]

@@ -13,6 +13,9 @@
 /* Description for the 'back button' accessibility trait */
 "trait.backbutton.description" = "Back Button.";
 
+/* Descriptor for the 'back' portion of the 'back button' accessibility trait */
+"back.descriptor" = "Back";
+
 /* Description for the 'tab' accessibility trait */
 "trait.tab.description" = "Tab.";
 

Example/SnapshotTests/ReferenceImages/_64/SnapshotTests.AccessibilitySnapshotTests/[email protected]

@@ -13,6 +13,9 @@
 /* Description for the 'back button' accessibility trait */
 "trait.backbutton.description" = "Кнопка назад.";
 
+/* Descriptor for the 'back' portion of the 'back button' accessibility trait */
+"back.descriptor" = "назад";
+
 /* Description for the 'tab' accessibility trait */
 "trait.tab.description" = "Вкладка.";
 

Example/SnapshotTests/ReferenceImages/_64/SnapshotTests.AccessibilitySnapshotTests/[email protected]

@@ -20,11 +20,15 @@ extension NSObject {
 
     /// Returns a tuple consisting of the `description` and (optionally) a `hint` that VoiceOver will read for the object.
     func accessibilityDescription(context: AccessibilityHierarchyParser.Context?) -> (description: String, hint: String?) {
-        var accessibilityDescription = accessibilityLabelOverride(for: context) ?? accessibilityLabel ?? ""
+        let strings = Strings(locale: accessibilityLanguage)
+
+        var accessibilityDescription =
+            accessibilityLabelOverride(for: context) ??
+        (hidesAccessibilityLabel(backDescriptor: strings.backDescriptor) ? "" :
+                                                            accessibilityLabel ?? "" )
 
         var hintDescription = accessibilityHint?.nonEmpty()
 
-        let strings = Strings(locale: accessibilityLanguage)
 
         let numberFormatter = NumberFormatter()
         if let localeIdentifier = accessibilityLanguage {
@@ -126,8 +130,9 @@ extension NSObject {
             case "2":
                 traitSpecifiers.append(strings.switchButtonMixedStateName)
             default:
-                // When the switch button trait is set, unknown accessibility values are omitted from the description.
-                break
+                if let accessibilityValue {
+                    traitSpecifiers.append(accessibilityValue)
+                }
             }
         }
 
@@ -307,6 +312,13 @@ extension NSObject {
             return false
         }
     }
+    
+    private func hidesAccessibilityLabel(backDescriptor: String) -> Bool {
+        // To prevent duplication, Back Button elements omit their label if it matches the localized "Back" descriptor.
+        guard accessibilityTraits.contains(.backButton),
+              let label = accessibilityLabel else { return false }
+        return label.lowercased() == backDescriptor.lowercased()
+    }
 
     // MARK: - Private Static Properties
 
@@ -325,6 +337,8 @@ extension NSObject {
         let buttonTraitName: String
 
         let backButtonTraitName: String
+        
+        let backDescriptor: String
 
         let tabTraitName: String
 
@@ -410,6 +424,11 @@ extension NSObject {
                 comment: "Description for the 'back button' accessibility trait",
                 locale: locale
             )
+            self.backDescriptor = "Back".localized(
+                key: "back.descriptor",
+                comment: "Descriptor for the 'back' portion of the 'back button' accessibility trait",
+                locale: locale
+            )
             self.tabTraitName = "Tab.".localized(
                 key: "trait.tab.description",
                 comment: "Description for the 'tab' accessibility trait",