Refresh the Xcode list on launch, sign-in and data source change

Xcodes/Backend/AppState+Update.swift

@@ -13,11 +13,14 @@ extension AppState {
     }
 
     func updateIfNeeded() {
+        // Never cancel a full refresh just because the window became active again.
+        if isUpdating, updateTaskIsFullRefresh { return }
         guard
-            isReadyForUpdate
+            isReadyForUpdate || !hasRefreshedAvailableXcodesThisLaunch
         else {
             updateTask?.cancel()
             let taskID = UUID()
+            updateTaskIsFullRefresh = false
             updateTaskID = taskID
             let task = Task { @MainActor in
                 defer {
@@ -35,8 +38,19 @@ extension AppState {
         update() as Void
     }
 
-    func update() {
-        guard !isUpdating else { return }
+    /// Refreshes installed and available Xcodes and runtimes.
+    /// - Parameter restartingInFlightUpdate: Cancel a running refresh and start over, e.g. when the
+    ///   data source or sign-in state changed and the running refresh would return stale results.
+    func update(restartingInFlightUpdate: Bool = false) {
+        if isUpdating {
+            // A quick installed-only rescan is always superseded; a full refresh only when asked.
+            guard restartingInFlightUpdate || !updateTaskIsFullRefresh else { return }
+            updateTask?.cancel()
+            updateTask = nil
+            updateTaskID = nil
+        }
+        hasRefreshedAvailableXcodesThisLaunch = true
+        updateTaskIsFullRefresh = true
         updateDownloadableRuntimes()
         updateInstalledRuntimes()
 
@@ -58,6 +72,9 @@ extension AppState {
                 Current.defaults.setDate(Current.date(), forKey: "lastUpdated")
             } catch is CancellationError {
             } catch {
+                // A restarted refresh can surface its cancellation as a URLError instead
+                guard !Task.isCancelled else { return }
+
                 // Prevent setting the app state error if it is an invalid session, we will present the sign in view instead
                 if error as? AuthenticationError != .invalidSession {
                     self.error = error

Xcodes/Backend/AppState.swift

@@ -45,7 +45,10 @@ class AppState: ObservableObject {
     @Published var authenticationState: AuthenticationState = .unauthenticated
     @Published var availableXcodes: [AvailableXcode] = [] {
         willSet {
-            if !Self.newlyAvailableXcodes(oldXcodes: availableXcodes, newXcodes: newValue).isEmpty {
+            if isChangingDataSource {
+                // The sources identify releases differently, so everything would look new.
+                isChangingDataSource = false
+            } else if !Self.newlyAvailableXcodes(oldXcodes: availableXcodes, newXcodes: newValue).isEmpty {
                 Current.notificationManager.scheduleNotification(title: localizeString("Notification.NewXcodeVersion.Title"), body: localizeString("Notification.NewXcodeVersion.Body"), category: .normal)
             }
             updateAllXcodes(
@@ -83,6 +86,12 @@ class AppState: ObservableObject {
     @Published var updateTask: Task<Void, Never>?
     var updateTaskID: UUID?
     var isUpdating: Bool { updateTask != nil }
+    /// Whether `updateTask` fetches available Xcodes, as opposed to only rescanning installed ones.
+    var updateTaskIsFullRefresh = false
+    /// The available Xcode list is always refreshed once per launch, regardless of cache age.
+    var hasRefreshedAvailableXcodesThisLaunch = false
+    /// Set while refreshing after a data source change, so the new list isn't announced as new versions
+    var isChangingDataSource = false
     @Published var presentedSheet: XcodesSheet? = nil
     @Published var isProcessingAuthRequest = false
     private var authenticationRequestID: UUID?
@@ -480,15 +489,30 @@ class AppState: ObservableObject {
                     authenticationTaskID = nil
                 }
             }
+            let wasAuthenticated = isAuthenticated
             do {
                 try await operation()
+                if !wasAuthenticated, isAuthenticated {
+                    refreshAfterSignIn()
+                }
             } catch is CancellationError {
             } catch {
                 // performAuthenticationRequest owns auth error presentation.
             }
         }
     }
 
+    private var isAuthenticated: Bool {
+        if case .authenticated = authenticationState { return true }
+        return false
+    }
+
+    /// Signing in unlocks the Apple data source, so restart any refresh that ran without a session.
+    private func refreshAfterSignIn() {
+        guard !isTesting else { return }
+        update(restartingInFlightUpdate: dataSource == .apple)
+    }
+
     func signOut() {
         clearLoginCredentials()
         Current.network.signout()

Xcodes/Frontend/Preferences/DownloadPreferencePane.swift

@@ -27,6 +27,11 @@ struct DownloadPreferencePane: View {
             }
             .groupBoxStyle(PreferencesGroupBoxStyle())
             .disabled(dataSource.isManaged)
+            .onChange(of: dataSource) {
+                // The cached list belongs to the previous source, so fetch the new one right away.
+                appState.isChangingDataSource = true
+                appState.update(restartingInFlightUpdate: true)
+            }
 
             GroupBox(label: Text("Downloader")) {
                 VStack(alignment: .leading) {

Xcodes/Frontend/XcodeList/MainToolbar.swift

@@ -16,7 +16,7 @@ struct MainToolbarModifier: ViewModifier {
         ToolbarItemGroup {
             ProgressButton(
                 isInProgress: appState.isUpdating,
-                action: appState.update
+                action: { appState.update() }
             ) {
                 Label("Refresh", systemImage: "arrow.clockwise")
             }

XcodesTests/AppStateUpdateTests.swift

@@ -45,6 +45,7 @@ class AppStateUpdateTests: XCTestCase {
             )
         ]
         Current.defaults.date = { _ in Date.mock() }
+        subject.hasRefreshedAvailableXcodesThisLaunch = true
 
         let continuations = AppStateUpdateTestLockedBox<[CheckedContinuation<ProcessOutput, Error>]>([])
         Current.shell.xcodeSelectPrintPath = {
@@ -78,6 +79,66 @@ class AppStateUpdateTests: XCTestCase {
         XCTAssertEqual(subject.selectedXcodePath, "/Applications/Xcode-Beta.app")
     }
 
+    func test_UpdateIfNeeded_FirstCallThisLaunch_RefreshesEvenWithFreshCache() async throws {
+        subject.availableXcodes = [
+            AvailableXcode(version: Version("0.0.0")!, url: URL(string: "https://apple.com/xcode.xip")!, filename: "mock.xip", releaseDate: nil)
+        ]
+        Current.defaults.date = { _ in Date.mock() }
+        XCTAssertFalse(subject.isReadyForUpdate)
+        let continuations = blockXcodeSelect()
+
+        subject.updateIfNeeded()
+        XCTAssertTrue(subject.updateTaskIsFullRefresh)
+        XCTAssertTrue(subject.hasRefreshedAvailableXcodesThisLaunch)
+        let fullRefreshTaskID = try XCTUnwrap(subject.updateTaskID)
+
+        // Becoming active again must not cancel the running full refresh
+        subject.updateIfNeeded()
+        XCTAssertEqual(subject.updateTaskID, fullRefreshTaskID)
+        XCTAssertTrue(subject.updateTaskIsFullRefresh)
+
+        await cancelUpdateTask(releasing: continuations)
+    }
+
+    func test_Update_OnlyRestartsRunningFullRefreshWhenAsked() async throws {
+        let continuations = blockXcodeSelect()
+
+        subject.update()
+        let firstTaskID = try XCTUnwrap(subject.updateTaskID)
+
+        subject.update()
+        XCTAssertEqual(subject.updateTaskID, firstTaskID)
+
+        subject.update(restartingInFlightUpdate: true)
+        XCTAssertNotNil(subject.updateTaskID)
+        XCTAssertNotEqual(subject.updateTaskID, firstTaskID)
+
+        await cancelUpdateTask(releasing: continuations)
+    }
+
+    private func blockXcodeSelect() -> AppStateUpdateTestLockedBox<[CheckedContinuation<ProcessOutput, Error>]> {
+        let continuations = AppStateUpdateTestLockedBox<[CheckedContinuation<ProcessOutput, Error>]>([])
+        Current.shell.xcodeSelectPrintPath = {
+            try await withCheckedThrowingContinuation { continuation in
+                continuations.withValue { $0.append(continuation) }
+            }
+        }
+        return continuations
+    }
+
+    private func cancelUpdateTask(releasing continuations: AppStateUpdateTestLockedBox<[CheckedContinuation<ProcessOutput, Error>]>) async {
+        let task = subject.updateTask
+        task?.cancel()
+        for _ in 0..<100 where continuations.read({ $0.isEmpty }) {
+            await Task.yield()
+        }
+        continuations.withValue { pending in
+            pending.forEach { $0.resume(throwing: CancellationError()) }
+            pending.removeAll()
+        }
+        await task?.value
+    }
+
     func testDoesNotReplaceInstallState() throws {
         subject.allXcodes = [
             Xcode(version: Version("0.0.0")!, installState: .installing(.unarchiving), selected: false, icon: nil)