updated preview tests and improved code

ElementX/Sources/Other/Extensions/String.swift

@@ -97,3 +97,15 @@ extension String {
         trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
     }
 }
+
+extension String {
+    static func makeCanonicalAlias(aliasLocalPart: Self?, serverName: Self?) -> Self? {
+        guard let aliasLocalPart = aliasLocalPart,
+              !aliasLocalPart.isEmpty,
+              let serverName = serverName,
+              !serverName.isEmpty else {
+            return nil
+        }
+        return "#\(aliasLocalPart):\(serverName)"
+    }
+}

ElementX/Sources/Screens/CreateRoom/CreateRoomViewModel.swift

@@ -154,7 +154,8 @@ class CreateRoomViewModel: CreateRoomViewModelType, CreateRoomViewModelProtocol
 
                 guard state.isKnockingFeatureEnabled,
                       !state.bindings.isRoomPrivate,
-                      let canonicalAlias = canonicalAlias(aliasLocalPart: aliasLocalPart) else {
+                      let canonicalAlias = String.makeCanonicalAlias(aliasLocalPart: aliasLocalPart,
+                                                                     serverName: state.serverName) else {
                     // While is empty or private room we don't change or display the error
                     return
                 }
@@ -209,7 +210,8 @@ class CreateRoomViewModel: CreateRoomViewModelType, CreateRoomViewModelProtocol
 
         // Better to double check the errors also when trying to create the room
         if state.isKnockingFeatureEnabled, !createRoomParameters.isRoomPrivate {
-            guard let canonicalAlias = canonicalAlias(aliasLocalPart: createRoomParameters.aliasLocalPart),
+            guard let canonicalAlias = String.makeCanonicalAlias(aliasLocalPart: createRoomParameters.aliasLocalPart,
+                                                                 serverName: state.serverName),
                   isRoomAliasFormatValid(alias: canonicalAlias) else {
                 state.aliasErrors = [.invalidSymbols]
                 return
@@ -271,14 +273,6 @@ class CreateRoomViewModel: CreateRoomViewModelType, CreateRoomViewModelProtocol
         }
     }
 
-    private func canonicalAlias(aliasLocalPart: String?) -> String? {
-        guard let aliasLocalPart,
-              !aliasLocalPart.isEmpty else {
-            return nil
-        }
-        return "#\(aliasLocalPart):\(state.serverName)"
-    }
-
     // MARK: Loading indicator
 
     private static let loadingIndicatorIdentifier = "\(CreateRoomViewModel.self)-Loading"

ElementX/Sources/Screens/EditRoomAddressScreen/EditRoomAddressScreenViewModel.swift

@@ -65,7 +65,8 @@ class EditRoomAddressScreenViewModel: EditRoomAddressScreenViewModelType, EditRo
                     return
                 }
 
-                guard let canonicalAlias = canonicalAlias(aliasLocalPart: aliasLocalPart) else {
+                guard let canonicalAlias = String.makeCanonicalAlias(aliasLocalPart: aliasLocalPart,
+                                                                     serverName: state.serverName) else {
                     // While is empty don't display the errors, since the save button is already disabled
                     state.aliasErrors.removeAll()
                     return
@@ -81,6 +82,12 @@ class EditRoomAddressScreenViewModel: EditRoomAddressScreenViewModelType, EditRo
 
                 state.aliasErrors.remove(.invalidSymbols)
 
+                guard aliasLocalPart != state.currentAliasLocalPart else {
+                    // Doesn't make sense to check the availability and display an error if the alias didn't change, the save button should also be disabled
+                    state.aliasErrors.remove(.alreadyExists)
+                    checkAliasAvailabilityTask = nil
+                    return
+                }
                 checkAliasAvailabilityTask = Task { [weak self] in
                     guard let self else {
                         return
@@ -99,8 +106,9 @@ class EditRoomAddressScreenViewModel: EditRoomAddressScreenViewModelType, EditRo
     }
 
     private func save() async {
-        guard let canonicalAlias = canonicalAlias(aliasLocalPart: state.bindings.desiredAliasLocalPart),
-              isRoomAliasFormatValid(alias: canonicalAlias) else {
+        guard let canonicalAlias = String.makeCanonicalAlias(aliasLocalPart: state.bindings.desiredAliasLocalPart,
+                                                             serverName: state.serverName),
+            isRoomAliasFormatValid(alias: canonicalAlias) else {
             state.aliasErrors = [.invalidSymbols]
             return
         }
@@ -118,11 +126,4 @@ class EditRoomAddressScreenViewModel: EditRoomAddressScreenViewModelType, EditRo
 
         // TODO: API calls to edit/add the alias and maybe also dismiss the view? (check with design)
     }
-
-    private func canonicalAlias(aliasLocalPart: String) -> String? {
-        guard !aliasLocalPart.isEmpty else {
-            return nil
-        }
-        return "#\(aliasLocalPart):\(state.serverName)"
-    }
 }

ElementX/Sources/Screens/EditRoomAddressScreen/View/EditRoomAddressScreen.swift

@@ -91,11 +91,13 @@ struct EditRoomAddressScreen_Previews: PreviewProvider, TestablePreview {
         NavigationStack {
             EditRoomAddressScreen(context: invalidSymbolsViewModel.context)
         }
+        .snapshotPreferences(delay: 1.2)
         .previewDisplayName("Invalid symbols")
 
         NavigationStack {
             EditRoomAddressScreen(context: alreadyExistingViewModel.context)
         }
+        .snapshotPreferences(delay: 1.2)
         .previewDisplayName("Already existing")
     }
 }