Repository: firebase/firebase-ios-sdk (language: cpp)

Issue:
Potential data race in Storage method
### Description

<img width="1103" alt="image" src="https://github.com/user-attachments/assets/5a6e70f0-0033-41cd-88f8-726241f8179c">


### Reproducing the issue

Define a storage instance and call `storage.reference(forURL: String)` from multiple threads and sometimes the warn in Xcode happened.
<img width="755" alt="image" src="https://github.com/user-attachments/assets/413d2c23-cfc4-4418-a5b3-7639b69b8d73">

```
 let task = Task {
            try await withCheckedThrowingContinuation { continuation in
                let storageReference = self.storage.reference(forURL: referencePath)
                storageReference.getData() { data, error in
                    if let error {
                        continuation.resume(throwing: error)
                        return
                    }
                    guard let data, !data.isEmpty else {
                        continuation.resume(throwing: Error.error)
                        return
                    }
                    continuation.resume(returning: data)
                }
            } as Data
        }

 return await task.value

```

### Firebase SDK Version

10.25.0

### Xcode Version

15.2

### Installation Method

Swift Package Manager

### Firebase Product(s)

Storage

### Targeted Platforms

iOS

### Relevant Log Output

_No response_

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Discussion / hints:
I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.
@jesus-mg-ios Thanks for the report. Would you check if #13381 fixes your test case?
Nevermind. `static` methods in an actor aren't thread safe. A fix will take more investigation.
Maybe a dispatch queue async with a  barrier flag could do the trick.
Thanks. First, we'll see if we can address by migrating those internal APIs to Swift concurrency sometime in the next few weeks.

Fix patch:
diff --git a/FirebaseStorage/CHANGELOG.md b/FirebaseStorage/CHANGELOG.md
index 7da1289bc6b..2738305acf3 100644
--- a/FirebaseStorage/CHANGELOG.md
+++ b/FirebaseStorage/CHANGELOG.md
@@ -1,3 +1,6 @@
+# Unreleased
+- [fixed] Fix a potential data race in Storage initialization. (#13369)
+
 # 11.0.0
 - [fixed] Updated error handling to support both Swift error enum handling and NSError error
   handling. Some of the Swift enums have additional parameters which may be a **breaking** change.
diff --git a/FirebaseStorage/Sources/Internal/StorageDeleteTask.swift b/FirebaseStorage/Sources/Internal/StorageDeleteTask.swift
index 37c80170a7a..d2917d18c49 100644
--- a/FirebaseStorage/Sources/Internal/StorageDeleteTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageDeleteTask.swift
@@ -24,11 +24,9 @@ import Foundation
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 enum StorageDeleteTask {
   static func deleteTask(reference: StorageReference,
-                         fetcherService: GTMSessionFetcherService,
                          queue: DispatchQueue,
                          completion: ((_: Data?, _: Error?) -> Void)?) {
     StorageInternalTask(reference: reference,
-                        fetcherService: fetcherService,
                         queue: queue,
                         httpMethod: "DELETE",
                         fetcherComment: "DeleteTask",
diff --git a/FirebaseStorage/Sources/Internal/StorageFetcherService.swift b/FirebaseStorage/Sources/Internal/StorageFetcherService.swift
new file mode 100644
index 00000000000..6d635ff001a
--- /dev/null
+++ b/FirebaseStorage/Sources/Internal/StorageFetcherService.swift
@@ -0,0 +1,87 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+#if COCOAPODS
+  import GTMSessionFetcher
+#else
+  import GTMSessionFetcherCore
+#endif
+
+/// Manage Storage's fetcherService
+@available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
+actor StorageFetcherService {
+  private var _fetcherService: GTMSessionFetcherService?
+
+  func fetcherService(_ storage: Storage) -> GTMSessionFetcherService {
+    if let _fetcherService {
+      return _fetcherService
+    }
+    let app = storage.app
+    if StorageFetcherService.fetcherServiceMap[app.name] == nil {
+      StorageFetcherService.fetcherServiceMap[app.name] = [:]
+    }
+    var fetcherService = StorageFetcherService.fetcherServiceMap[app.name]?[storage.storageBucket]
+    if fetcherService == nil {
+      fetcherService = GTMSessionFetcherService()
+      fetcherService?.isRetryEnabled = true
+      fetcherService?.retryBlock = retryWhenOffline
+      fetcherService?.allowLocalhostRequest = true
+      fetcherService?.maxRetryInterval = storage.maxOperationRetryInterval
+      fetcherService?.testBlock = testBlock
+      let authorizer = StorageTokenAuthorizer(
+        googleAppID: app.options.googleAppID,
+        callbackQueue: storage.callbackQueue,
+        authProvider: storage.auth,
+        appCheck: storage.appCheck
+      )
+      fetcherService?.authorizer = authorizer
+      StorageFetcherService.fetcherServiceMap[app.name]?[storage.storageBucket] = fetcherService
+    }
+    if storage.usesEmulator {
+      fetcherService?.allowLocalhostRequest = true
+      fetcherService?.allowedInsecureSchemes = ["http"]
+    }
+    _fetcherService = fetcherService
+    return fetcherService!
+  }
+
+  /// Update the testBlock for unit testing. Save it as a property since this may be called before
+  /// fetcherService is initialized.
+  func updateTestBlock(_ block: @escaping GTMSessionFetcherTestBlock) {
+    testBlock = block
+    if let _fetcherService {
+      _fetcherService.testBlock = testBlock
+    }
+  }
+
+  private var testBlock: GTMSessionFetcherTestBlock?
+
+  /// Map of apps to a dictionary of buckets to GTMSessionFetcherService.
+  private static var fetcherServiceMap: [String: [String: GTMSessionFetcherService]] = [:]
+
+  private var retryWhenOffline: GTMSessionFetcherRetryBlock = {
+    (suggestedWillRetry: Bool,
+     error: Error?,
+     response: @escaping GTMSessionFetcherRetryResponse) in
+    var shouldRetry = suggestedWillRetry
+    // GTMSessionFetcher does not consider being offline a retryable error, but we do, so we
+    // special-case it here.
+    if !shouldRetry, error != nil {
+      shouldRetry = (error as? NSError)?.code == URLError.notConnectedToInternet.rawValue
+    }
+    response(shouldRetry)
+  }
+}
diff --git a/FirebaseStorage/Sources/Internal/StorageGetDownloadURLTask.swift b/FirebaseStorage/Sources/Internal/StorageGetDownloadURLTask.swift
index 868fad36f45..be4e99f4066 100644
--- a/FirebaseStorage/Sources/Internal/StorageGetDownloadURLTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageGetDownloadURLTask.swift
@@ -14,21 +14,13 @@
 
 import Foundation
 
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
-
 /// Task which provides the ability to get a download URL for an object in Firebase Storage.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 enum StorageGetDownloadURLTask {
   static func getDownloadURLTask(reference: StorageReference,
-                                 fetcherService: GTMSessionFetcherService,
                                  queue: DispatchQueue,
                                  completion: ((_: URL?, _: Error?) -> Void)?) {
     StorageInternalTask(reference: reference,
-                        fetcherService: fetcherService,
                         queue: queue,
                         httpMethod: "GET",
                         fetcherComment: "GetDownloadURLTask") { (data: Data?, error: Error?) in
diff --git a/FirebaseStorage/Sources/Internal/StorageGetMetadataTask.swift b/FirebaseStorage/Sources/Internal/StorageGetMetadataTask.swift
index 5886f2ae551..dffbe26c46c 100644
--- a/FirebaseStorage/Sources/Internal/StorageGetMetadataTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageGetMetadataTask.swift
@@ -14,21 +14,13 @@
 
 import Foundation
 
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
-
 /// Task which provides the ability to delete an object in Firebase Storage.
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 enum StorageGetMetadataTask {
   static func getMetadataTask(reference: StorageReference,
-                              fetcherService: GTMSessionFetcherService,
                               queue: DispatchQueue,
                               completion: ((_: StorageMetadata?, _: Error?) -> Void)?) {
     StorageInternalTask(reference: reference,
-                        fetcherService: fetcherService,
                         queue: queue,
                         httpMethod: "GET",
                         fetcherComment: "GetMetadataTask") { (data: Data?, error: Error?) in
diff --git a/FirebaseStorage/Sources/Internal/StorageInternalTask.swift b/FirebaseStorage/Sources/Internal/StorageInternalTask.swift
index 3d2233e4b90..82429009e29 100644
--- a/FirebaseStorage/Sources/Internal/StorageInternalTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageInternalTask.swift
@@ -27,35 +27,35 @@ class StorageInternalTask: StorageTask {
 
   @discardableResult
   init(reference: StorageReference,
-       fetcherService: GTMSessionFetcherService,
        queue: DispatchQueue,
        request: URLRequest? = nil,
        httpMethod: String,
        fetcherComment: String,
        completion: ((_: Data?, _: Error?) -> Void)?) {
-    super.init(reference: reference, service: fetcherService, queue: queue)
+    super.init(reference: reference, queue: queue)
 
     // Prepare a task and begins execution.
     dispatchQueue.async { [self] in
       self.state = .queueing
-      var request = request ?? self.baseRequest
-      request.httpMethod = httpMethod
-      request.timeoutInterval = self.reference.storage.maxOperationRetryTime
+      Task {
+        let fetcherService = await reference.storage.fetcherService
+          .fetcherService(reference.storage)
 
-      let fetcher = self.fetcherService.fetcher(with: request)
-      fetcher.comment = fetcherComment
-      self.fetcher = fetcher
+        var request = request ?? self.baseRequest
+        request.httpMethod = httpMethod
+        request.timeoutInterval = self.reference.storage.maxOperationRetryTime
 
-      Task {
-        let callbackQueue = reference.storage.fetcherService != nil ?
-          reference.storage.fetcherServiceForApp.callbackQueue : DispatchQueue.main
+        let fetcher = fetcherService.fetcher(with: request)
+        fetcher.comment = fetcherComment
+        self.fetcher = fetcher
+        let callbackQueue = reference.storage.callbackQueue
         do {
           let data = try await self.fetcher?.beginFetch()
-          callbackQueue?.async {
+          callbackQueue.async {
             completion?(data, nil)
           }
         } catch {
-          callbackQueue?.async {
+          callbackQueue.async {
             completion?(nil, StorageErrorCode.error(withServerError: error as NSError,
                                                     ref: self.reference))
           }
diff --git a/FirebaseStorage/Sources/Internal/StorageListTask.swift b/FirebaseStorage/Sources/Internal/StorageListTask.swift
index c8a69c2ba24..8d9369a6768 100644
--- a/FirebaseStorage/Sources/Internal/StorageListTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageListTask.swift
@@ -14,17 +14,10 @@
 
 import Foundation
 
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
-
 /// A Task that lists the entries under a StorageReference
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 enum StorageListTask {
   static func listTask(reference: StorageReference,
-                       fetcherService: GTMSessionFetcherService,
                        queue: DispatchQueue,
                        pageSize: Int64?,
                        previousPageToken: String?,
@@ -60,7 +53,6 @@ enum StorageListTask {
     )
 
     StorageInternalTask(reference: reference,
-                        fetcherService: fetcherService,
                         queue: queue,
                         request: request,
                         httpMethod: "GET",
diff --git a/FirebaseStorage/Sources/Internal/StorageUpdateMetadataTask.swift b/FirebaseStorage/Sources/Internal/StorageUpdateMetadataTask.swift
index 470cf5f7144..12f4924576f 100644
--- a/FirebaseStorage/Sources/Internal/StorageUpdateMetadataTask.swift
+++ b/FirebaseStorage/Sources/Internal/StorageUpdateMetadataTask.swift
@@ -14,17 +14,10 @@
 
 import Foundation
 
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
-
 /// A Task that lists the entries under a StorageReference
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 enum StorageUpdateMetadataTask {
   static func updateMetadataTask(reference: StorageReference,
-                                 fetcherService: GTMSessionFetcherService,
                                  queue: DispatchQueue,
                                  metadata: StorageMetadata,
                                  completion: ((_: StorageMetadata?, _: Error?) -> Void)?) {
@@ -37,7 +30,6 @@ enum StorageUpdateMetadataTask {
     }
 
     StorageInternalTask(reference: reference,
-                        fetcherService: fetcherService,
                         queue: queue,
                         request: request,
                         httpMethod: "PATCH",
diff --git a/FirebaseStorage/Sources/Storage.swift b/FirebaseStorage/Sources/Storage.swift
index 3ac124343ed..c9a33522b03 100644
--- a/FirebaseStorage/Sources/Storage.swift
+++ b/FirebaseStorage/Sources/Storage.swift
@@ -17,11 +17,6 @@ import Foundation
 import FirebaseAppCheckInterop
 import FirebaseAuthInterop
 import FirebaseCore
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
 
 // Avoids exposing internal FirebaseCore APIs to Swift users.
 @_implementationOnly import FirebaseCoreExtension
@@ -129,7 +124,7 @@ import FirebaseCore
   /// - Returns: An instance of `StorageReference` referencing the root of the storage bucket.
   @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
   @objc open func reference() -> StorageReference {
-    ensureConfigured()
+    configured = true
     let path = StoragePath(with: storageBucket)
     return StorageReference(storage: self, path: path)
   }
@@ -146,7 +141,7 @@ import FirebaseCore
   /// initialize this Storage instance.
   @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
   @objc open func reference(forURL url: String) -> StorageReference {
-    ensureConfigured()
+    configured = true
     do {
       let path = try StoragePath.path(string: url)
 
@@ -178,7 +173,7 @@ import FirebaseCore
   /// - Throws: Throws an Error if `url` is not associated with the `FirebaseApp` used to initialize
   ///     this Storage instance.
   open func reference(for url: URL) throws -> StorageReference {
-    ensureConfigured()
+    configured = true
     var path: StoragePath
     do {
       path = try StoragePath.path(string: url.absoluteString)
@@ -222,7 +217,7 @@ import FirebaseCore
     guard port >= 0 else {
       fatalError("Invalid port argument: Port must be greater or equal to zero.")
     }
-    guard fetcherService == nil else {
+    guard configured == false else {
       fatalError("Cannot connect to emulator after Storage SDK initialization. " +
         "Call useEmulator(host:port:) before creating a Storage " +
         "reference or trying to load data.")
@@ -254,14 +249,7 @@ import FirebaseCore
 
   // MARK: - Internal and Private APIs
 
-  var fetcherService: GTMSessionFetcherService?
-
-  var fetcherServiceForApp: GTMSessionFetcherService {
-    guard let value = fetcherService else {
-      fatalError("Internal error: fetcherServiceForApp not yet configured.")
-    }
-    return value
-  }
+  let fetcherService = StorageFetcherService()
 
   let dispatchQueue: DispatchQueue
 
@@ -275,7 +263,6 @@ import FirebaseCore
     host = "firebasestorage.googleapis.com"
     scheme = "https"
     port = 443
-    fetcherService = nil // Configured in `ensureConfigured()`
     // Must be a serial queue.
     dispatchQueue = DispatchQueue(label: "com.google.firebase.storage")
     maxDownloadRetryTime = 600.0
@@ -286,57 +273,13 @@ import FirebaseCore
     maxUploadRetryInterval = Storage.computeRetryInterval(fromRetryTime: maxUploadRetryTime)
   }
 
-  /// Map of apps to a dictionary of buckets to GTMSessionFetcherService.
-  private static let fetcherServiceLock = NSObject()
-  private static var fetcherServiceMap: [String: [String: GTMSessionFetcherService]] = [:]
-  private static var retryWhenOffline: GTMSessionFetcherRetryBlock = {
-    (suggestedWillRetry: Bool,
-     error: Error?,
-     response: @escaping GTMSessionFetcherRetryResponse) in
-    var shouldRetry = suggestedWillRetry
-    // GTMSessionFetcher does not consider being offline a retryable error, but we do, so we
-    // special-case it here.
-    if !shouldRetry, error != nil {
-      shouldRetry = (error as? NSError)?.code == URLError.notConnectedToInternet.rawValue
-    }
-    response(shouldRetry)
-  }
+  let auth: AuthInterop?
+  let appCheck: AppCheckInterop?
+  let storageBucket: String
+  var usesEmulator = false
 
-  private static func initFetcherServiceForApp(_ app: FirebaseApp,
-                                               _ bucket: String,
-                                               _ auth: AuthInterop?,
-                                               _ appCheck: AppCheckInterop?,
-                                               _ callbackQueue: DispatchQueue)
-    -> GTMSessionFetcherService {
-    objc_sync_enter(fetcherServiceLock)
-    defer { objc_sync_exit(fetcherServiceLock) }
-    var bucketMap = fetcherServiceMap[app.name]
-    if bucketMap == nil {
-      bucketMap = [:]
-      fetcherServiceMap[app.name] = bucketMap
-    }
-    var fetcherService = bucketMap?[bucket]
-    if fetcherService == nil {
-      fetcherService = GTMSessionFetcherService()
-      fetcherService?.isRetryEnabled = true
-      fetcherService?.retryBlock = retryWhenOffline
-      fetcherService?.allowLocalhostRequest = true
-      let authorizer = StorageTokenAuthorizer(
-        googleAppID: app.options.googleAppID,
-        callbackQueue: callbackQueue,
-        authProvider: auth,
-        appCheck: appCheck
-      )
-      fetcherService?.authorizer = authorizer
-      bucketMap?[bucket] = fetcherService
-    }
-    return fetcherService!
-  }
-
-  private let auth: AuthInterop?
-  private let appCheck: AppCheckInterop?
-  private let storageBucket: String
-  private var usesEmulator: Bool = false
+  /// Once `configured` is true, the emulator can no longer be enabled.
+  var configured = false
 
   /// A map of active instances, grouped by app. Keys are FirebaseApp names and values are
   /// instances of Storage associated with the given app.
@@ -354,9 +297,9 @@ import FirebaseCore
 
   /// Performs a crude translation of the user provided timeouts to the retry intervals that
   /// GTMSessionFetcher accepts. GTMSessionFetcher times out operations if the time between
-  /// individual
-  /// retry attempts exceed a certain threshold, while our API contract looks at the total observed
-  /// time of the operation (i.e. the sum of all retries).
+  /// individual retry attempts exceed a certain threshold, while our API contract looks at the
+  /// total
+  /// observed time of the operation (i.e. the sum of all retries).
   /// @param retryTime A timeout that caps the sum of all retry attempts
   /// @return A timeout that caps the timeout of the last retry attempt
   static func computeRetryInterval(fromRetryTime retryTime: TimeInterval) -> TimeInterval {
@@ -374,19 +317,6 @@ import FirebaseCore
     return lastInterval
   }
 
-  /// Configures the storage instance. Freezes the host setting.
-  private func ensureConfigured() {
-    guard fetcherService == nil else {
-      return
-    }
-    fetcherService = Storage.initFetcherServiceForApp(app, storageBucket, auth, appCheck,
-                                                      callbackQueue)
-    if usesEmulator {
-      fetcherService?.allowLocalhostRequest = true
-      fetcherService?.allowedInsecureSchemes = ["http"]
-    }
-  }
-
   private static func bucket(for app: FirebaseApp) -> String {
     guard let bucket = app.options.storageBucket else {
       fatalError("No default Storage bucket found. Did you configure Firebase Storage properly?")
diff --git a/FirebaseStorage/Sources/StorageDownloadTask.swift b/FirebaseStorage/Sources/StorageDownloadTask.swift
index 5bfe3ee4b50..0f0776c777a 100644
--- a/FirebaseStorage/Sources/StorageDownloadTask.swift
+++ b/FirebaseStorage/Sources/StorageDownloadTask.swift
@@ -39,7 +39,9 @@ open class StorageDownloadTask: StorageObservableTask, StorageTaskManagement {
    * Prepares a task and begins execution.
    */
   @objc open func enqueue() {
-    enqueueImplementation()
+    Task {
+      await enqueueImplementation()
+    }
   }
 
   /**
@@ -80,7 +82,9 @@ open class StorageDownloadTask: StorageObservableTask, StorageTaskManagement {
       self.state = .resuming
       self.fire(for: .resume, snapshot: self.snapshot)
       self.state = .running
-      self.enqueueImplementation(resumeWith: self.downloadData)
+      Task {
+        await self.enqueueImplementation(resumeWith: self.downloadData)
+      }
     }
   }
 
@@ -93,90 +97,87 @@ open class StorageDownloadTask: StorageObservableTask, StorageTaskManagement {
   // MARK: - Internal Implementations
 
   override init(reference: StorageReference,
-                service: GTMSessionFetcherService,
                 queue: DispatchQueue,
                 file: URL?) {
-    super.init(reference: reference, service: service, queue: queue, file: file)
+    super.init(reference: reference, queue: queue, file: file)
   }
 
   deinit {
     self.fetcher?.stopFetching()
   }
 
-  private func enqueueImplementation(resumeWith resumeData: Data? = nil) {
-    dispatchQueue.async { [weak self] in
-      guard let self = self else { return }
-      self.state = .queueing
-      var request = self.baseRequest
-      request.httpMethod = "GET"
-      request.timeoutInterval = self.reference.storage.maxDownloadRetryTime
-      var components = URLComponents(url: request.url!, resolvingAgainstBaseURL: false)
-      components?.query = "alt=media"
-      request.url = components?.url
-
-      var fetcher: GTMSessionFetcher
-      if let resumeData {
-        fetcher = GTMSessionFetcher(downloadResumeData: resumeData)
-        fetcher.comment = "Resuming DownloadTask"
-      } else {
-        fetcher = self.fetcherService.fetcher(with: request)
-        fetcher.comment = "Starting DownloadTask"
-      }
-      fetcher.maxRetryInterval = self.reference.storage.maxDownloadRetryInterval
-
-      if let fileURL {
-        // Handle file downloads
-        fetcher.destinationFileURL = fileURL
-        fetcher.downloadProgressBlock = { [weak self] (bytesWritten: Int64,
-                                                       totalBytesWritten: Int64,
-                                                       totalBytesExpectedToWrite: Int64) in
-            guard let self = self else { return }
-            self.state = .progress
-            self.progress.completedUnitCount = totalBytesWritten
-            self.progress.totalUnitCount = totalBytesExpectedToWrite
-            self.fire(for: .progress, snapshot: self.snapshot)
-            self.state = .running
-        }
-      } else {
-        // Handle data downloads
-        fetcher.receivedProgressBlock = { [weak self] (bytesWritten: Int64,
-                                                       totalBytesWritten: Int64) in
-            guard let self = self else { return }
-            self.state = .progress
-            self.progress.completedUnitCount = totalBytesWritten
-            if let totalLength = self.fetcher?.response?.expectedContentLength {
-              self.progress.totalUnitCount = totalLength
-            }
-            self.fire(for: .progress, snapshot: self.snapshot)
-            self.state = .running
-        }
-      }
-      self.fetcher = fetcher
-      self.state = .running
-      Task {
-        do {
-          let data = try await self.fetcher?.beginFetch()
-          // Fire last progress updates
-          self.fire(for: .progress, snapshot: self.snapshot)
+  private func enqueueImplementation(resumeWith resumeData: Data? = nil) async {
+    state = .queueing
 
-          // Download completed successfully, fire completion callbacks
-          self.state = .success
-          if let data {
-            self.downloadData = data
+    var request = baseRequest
+    request.httpMethod = "GET"
+    request.timeoutInterval = reference.storage.maxDownloadRetryTime
+    var components = URLComponents(url: request.url!, resolvingAgainstBaseURL: false)
+    components?.query = "alt=media"
+    request.url = components?.url
+
+    var fetcher: GTMSessionFetcher
+    if let resumeData {
+      fetcher = GTMSessionFetcher(downloadResumeData: resumeData)
+      fetcher.comment = "Resuming DownloadTask"
+    } else {
+      let fetcherService = await reference.storage.fetcherService.fetcherService(reference.storage)
+
+      fetcher = fetcherService.fetcher(with: request)
+      fetcher.comment = "Starting DownloadTask"
+    }
+    fetcher.maxRetryInterval = reference.storage.maxDownloadRetryInterval
+
+    if let fileURL {
+      // Handle file downloads
+      fetcher.destinationFileURL = fileURL
+      fetcher.downloadProgressBlock = { [weak self] (bytesWritten: Int64,
+                                                     totalBytesWritten: Int64,
+                                                     totalBytesExpectedToWrite: Int64) in
+          guard let self = self else { return }
+          self.state = .progress
+          self.progress.completedUnitCount = totalBytesWritten
+          self.progress.totalUnitCount = totalBytesExpectedToWrite
+          self.fire(for: .progress, snapshot: self.snapshot)
+          self.state = .running
+      }
+    } else {
+      // Handle data downloads
+      fetcher.receivedProgressBlock = { [weak self] (bytesWritten: Int64,
+                                                     totalBytesWritten: Int64) in
+          guard let self = self else { return }
+          self.state = .progress
+          self.progress.completedUnitCount = totalBytesWritten
+          if let totalLength = self.fetcher?.response?.expectedContentLength {
+            self.progress.totalUnitCount = totalLength
           }
-          self.fire(for: .success, snapshot: self.snapshot)
-        } catch {
           self.fire(for: .progress, snapshot: self.snapshot)
-          self.state = .failed
-          self.error = StorageErrorCode.error(
-            withServerError: error as NSError,
-            ref: self.reference
-          )
-          self.fire(for: .failure, snapshot: self.snapshot)
-        }
-        self.removeAllObservers()
+          self.state = .running
+      }
+    }
+    self.fetcher = fetcher
+    state = .running
+    do {
+      let data = try await self.fetcher?.beginFetch()
+      // Fire last progress updates
+      fire(for: .progress, snapshot: snapshot)
+
+      // Download completed successfully, fire completion callbacks
+      state = .success
+      if let data {
+        downloadData = data
       }
+      fire(for: .success, snapshot: snapshot)
+    } catch {
+      fire(for: .progress, snapshot: snapshot)
+      state = .failed
+      self.error = StorageErrorCode.error(
+        withServerError: error as NSError,
+        ref: reference
+      )
+      fire(for: .failure, snapshot: snapshot)
     }
+    removeAllObservers()
   }
 
   func cancel(withError error: NSError) {
@@ -186,6 +187,7 @@ open class StorageDownloadTask: StorageObservableTask, StorageTaskManagement {
       self.fetcher?.stopFetching()
       self.error = error
       self.fire(for: .failure, snapshot: self.snapshot)
+      self.removeAllObservers()
     }
   }
 }
diff --git a/FirebaseStorage/Sources/StorageObservableTask.swift b/FirebaseStorage/Sources/StorageObservableTask.swift
index 6567482b2e9..4330526496e 100644
--- a/FirebaseStorage/Sources/StorageObservableTask.swift
+++ b/FirebaseStorage/Sources/StorageObservableTask.swift
@@ -14,12 +14,6 @@
 
 import Foundation
 
-#if COCOAPODS
-  import GTMSessionFetcher
-#else
-  import GTMSessionFetcherCore
-#endif
-
 /**
  * An extended `StorageTask` providing observable semantics that can be used for responding to changes
  * in task state.
@@ -134,7 +128,6 @@ import Foundation
   // MARK: - Internal Implementations
 
   init(reference: StorageReference,
-       service: GTMSessionFetcherService,
        queue: DispatchQueue,
        file: URL?) {
     handlerDictionaries = [
@@ -146,7 +139,7 @@ import Foundation
     ]
     handleToStatusMap = [:]
     fileURL = file
-    super.init(reference: reference, service: service, queue: queue)
+    super.init(reference: reference, queue: queue)
   }
 
   func updateHandlerDictionary(for status: StorageTaskStatus,
diff --git a/FirebaseStorage/Sources/StorageReference.swift b/FirebaseStorage/Sources/StorageReference.swift
index d341bbdf14d..26d4b27ee5a 100644
--- a/FirebaseStorage/Sources/StorageReference.swift
+++ b/FirebaseStorage/Sources/StorageReference.swift
@@ -128,7 +128,6 @@ import Foundation
       putMetadata.name = (path as NSString).lastPathComponent as String
     }
     let task = StorageUploadTask(reference: self,
-                                 service: storage.fetcherServiceForApp,
                                  queue: storage.dispatchQueue,
                                  data: uploadData,
                                  metadata: putMetadata)
@@ -175,7 +174,6 @@ import Foundation
       putMetadata.name = (path as NSString).lastPathComponent as String
     }
     let task = StorageUploadTask(reference: self,
-                                 service: storage.fetcherServiceForApp,
                                  queue: storage.dispatchQueue,
                                  file: fileURL,
                                  metadata: putMetadata)
@@ -199,9 +197,7 @@ import Foundation
   @objc(dataWithMaxSize:completion:) @discardableResult
   open func getData(maxSize: Int64,
                     completion: @escaping ((_: Data?, _: Error?) -> Void)) -> StorageDownloadTask {
-    let fetcherService = storage.fetcherServiceForApp
     let task = StorageDownloadTask(reference: self,
-                                   service: fetcherService,
                                    queue: storage.dispatchQueue,
                                    file: nil)
 
@@ -240,9 +236,7 @@ import Foundation
   ///     or an error on failure.
   @objc(downloadURLWithCompletion:)
   open func downloadURL(completion: @escaping ((_: URL?, _: Error?) -> Void)) {
-    let fetcherService = storage.fetcherServiceForApp
     StorageGetDownloadURLTask.getDownloadURLTask(reference: self,
-                                                 fetcherService: fetcherService,
                                                  queue: storage.dispatchQueue,
                                                  completion: completion)
   }
@@ -252,7 +246,6 @@ import Foundation
   /// in the Firebase Console.
   /// - Throws: An error if the download URL could not be retrieved.
   /// - Returns: The URL on success.
-  @available(iOS 13, tvOS 13, macOS 10.15, watchOS 8, *)
   open func downloadURL() async throws -> URL {
     return try await withCheckedThrowingContinuation { continuation in
       self.downloadURL { result in
@@ -280,9 +273,7 @@ import Foundation
   @objc(writeToFile:completion:) @discardableResult
   open func write(toFile fileURL: URL,
                   completion: ((_: URL?, _: Error?) -> Void)?) -> StorageDownloadTask {
-    let fetcherService = storage.fetcherServiceForApp
     let task = StorageDownloadTask(reference: self,
-                                   service: fetcherService,
                                    queue: storage.dispatchQueue,
                                    file: fileURL)
 
@@ -322,7 +313,6 @@ import Foundation
   ///       the current `StorageReference`.
   @objc(listAllWithCompletion:)
   open func listAll(completion: @escaping ((_: StorageListResult?, _: Error?) -> Void)) {
-    let fetcherService = storage.fetcherServiceForApp
     var prefixes = [StorageReference]()
     var items = [StorageReference]()
 
@@ -343,7 +333,6 @@ import Foundation
 
       if let pageToken = listResult.pageToken {
         StorageListTask.listTask(reference: strongSelf,
-                                 fetcherService: fetcherService,
                                  queue: strongSelf.storage.dispatchQueue,
                                  pageSize: nil,
                                  previousPageToken: pageToken,
@@ -358,7 +347,6 @@ import Foundation
     }
 
     StorageListTask.listTask(reference: self,
-                             fetcherService: fetcherService,
                              queue: storage.dispatchQueue,
                              pageSize: nil,
                              previousPageToken: nil,
@@ -372,7 +360,6 @@ import Foundation
   /// `listAll()` is only available for projects using Firebase Rules Version 2.
   /// - Throws: An error if the list operation failed.
   /// - Returns: All items and prefixes under the current `StorageReference`.
-  @available(iOS 13, tvOS 13, macOS 10.15, watchOS 8, *)
   open func listAll() async throws -> StorageListResult {
     return try await withCheckedThrowingContinuation { continuation in
       self.listAll { result in
@@ -401,9 +388,7 @@ import Foundation
         message: "Argument 'maxResults' must be between 1 and 1000 inclusive."
       ))
     } else {
-      let fetcherService = storage.fetcherServiceForApp
       StorageListTask.listTask(reference: self,
-                               fetcherService: fetcherService,
                                queue: storage.dispatchQueue,
                                pageSize: maxResults,
                                previousPageToken: nil,
@@ -436,9 +421,7 @@ import Foundation
         message: "Argument 'maxResults' must be between 1 and 1000 inclusive."
       ))
     } else {
-      let fetcherService = storage.fetcherServiceForApp
       StorageListTask.listTask(reference: self,
-                               fetcherService: fetcherService,
                                queue: storage.dispatchQueue,
                                pageSize: maxResults,
                                previousPageToken: pageToken,
@@ -453,9 +436,7 @@ import Foundation
   ///   or an error on failure.
   @objc(metadataWithCompletion:)
   open func getMetadata(completion: @escaping ((_: StorageMetadata?, _: Error?) -> Void)) {
-    let fetcherService = storage.fetcherServiceForApp
     StorageGetMetadataTask.getMetadataTask(reference: self,
-                                           fetcherService: fetcherService,
                                            queue: storage.dispatchQueue,
                                            completion: completion)
   }
@@ -463,7 +444,6 @@ import Foundation
   /// Retrieves metadata associated with an object at the current path.
   /// - Throws: An error if the object metadata could not be retrieved.
   /// - Returns: The object metadata on success.
-  @available(iOS 13, tvOS 13, macOS 10.15, watchOS 8, *)
   open func getMetadata() async throws -> StorageMetadata {
     return try await withCheckedThrowingContinuation { continuation in
       self.getMetadata { result in
@@ -480,9 +460,7 @@ import Foundation
   @objc(updateMetadata:completion:)
   open func updateMetadata(_ metadata: StorageMetadata,
                            completion: ((_: StorageMetadata?, _: Error?) -> Void)?) {
-    let fetcherService = storage.fetcherServiceForApp
     StorageUpdateMetadataTask.updateMetadataTask(reference: self,
-                                                 fetcherService: fetcherService,
                                                  queue: storage.dispatchQueue,
                                                  metadata: metadata,
                                                  completion: completion)
@@ -492,7 +470,6 @@ import Foundation
   /// - Parameter metadata: A `StorageMetadata` object with the metadata to update.
   /// - Throws: An error if the metadata update operation failed.
   /// - Returns: The object metadata on success.
-  @available(iOS 13, tvOS 13, macOS 10.15, watchOS 8, *)
   open func updateMetadata(_ metadata: StorageMetadata) async throws -> StorageMetadata {
     return try await withCheckedThrowingContinuation { continuation in
       self.updateMetadata(metadata) { result in
@@ -507,21 +484,18 @@ import Foundation
   /// - Parameter completion: A completion block which returns a nonnull error on failure.
   @objc(deleteWithCompletion:)
   open func delete(completion: ((_: Error?) -> Void)?) {
-    let fetcherService = storage.fetcherServiceForApp
     let completionWrap = { (_: Data?, error: Error?) in
       if let completion {
         completion(error)
       }
     }
     StorageDeleteTask.deleteTask(reference: self,
-                                 fetcherService: fetcherService,
                                  queue: storage.dispatchQueue,
                                  completion: completionWrap)
   }
 
   /// Deletes the object at the current path.
   /// - Throws: An error if the delete operation failed.
-  @available(iOS 13, tvOS 13, macOS 10.15, watchOS 8, *)
   open func delete() async throws {
     return try await withCheckedThrowingContinuation { continuation in
       self.delete { error in
@@ -590,7 +564,7 @@ import Foundation
                                          completion: ((_: StorageMetadata?, _: Error?) -> Void)?) {
     if let completion {
       task.completionMetadata = completion
-      let callbackQueue = storage.fetcherServiceForApp.callbackQueue ?? DispatchQueue.main
+      let callbackQueue = storage.callbackQueue
 
       task.observe(.success) { snapshot in
         callbackQueue.async {
diff --git a/FirebaseStorage/Sources/StorageTask.swift b/FirebaseStorage/Sources/StorageTask.swift
index 356d131373b..a745b50db32 100644
--- a/FirebaseStorage/Sources/StorageTask.swift
+++ b/FirebaseStorage/Sources/StorageTask.swift
@@ -81,16 +81,11 @@ import Foundation
    */
   let dispatchQueue: DispatchQueue
 
-  let fetcherService: GTMSessionFetcherService
-
   let baseRequest: URLRequest
 
   init(reference: StorageReference,
-       service: GTMSessionFetcherService,
        queue: DispatchQueue) {
     self.reference = reference
-    fetcherService = service
-    fetcherService.maxRetryInterval = reference.storage.maxOperationRetryInterval
     dispatchQueue = queue
     state = .unknown
     progress = Progress(totalUnitCount: 0)
diff --git a/FirebaseStorage/Sources/StorageUploadTask.swift b/FirebaseStorage/Sources/StorageUploadTask.swift
index a0a4bea7eac..5870d4e3689 100644
--- a/FirebaseStorage/Sources/StorageUploadTask.swift
+++ b/FirebaseStorage/Sources/StorageUploadTask.swift
@@ -54,68 +54,71 @@ import Foundation
       }
 
       self.state = .queueing
-      var request = self.baseRequest
-      request.httpMethod = "POST"
-      request.timeoutInterval = self.reference.storage.maxUploadRetryTime
 
       let dataRepresentation = self.uploadMetadata.dictionaryRepresentation()
       let bodyData = try? JSONSerialization.data(withJSONObject: dataRepresentation)
 
-      request.httpBody = bodyData
-      request.setValue("application/json; charset=UTF-8", forHTTPHeaderField: "Content-Type")
-      if let count = bodyData?.count {
-        request.setValue("\(count)", forHTTPHeaderField: "Content-Length")
-      }
+      Task {
+        let fetcherService = await reference.storage.fetcherService
+          .fetcherService(reference.storage)
+        var request = self.baseRequest
+        request.httpMethod = "POST"
+        request.timeoutInterval = self.reference.storage.maxUploadRetryTime
+        request.httpBody = bodyData
+        request.setValue("application/json; charset=UTF-8", forHTTPHeaderField: "Content-Type")
+        if let count = bodyData?.count {
+          request.setValue("\(count)", forHTTPHeaderField: "Content-Length")
+        }
 
-      var components = URLComponents(url: request.url!, resolvingAgainstBaseURL: false)
-      if components?.host == "www.googleapis.com",
-         let path = components?.path {
-        components?.percentEncodedPath = "/upload\(path)"
-      }
-      guard let path = self.GCSEscapedString(self.uploadMetadata.path) else {
-        fatalError("Internal error enqueueing a Storage task")
-      }
-      components?.percentEncodedQuery = "uploadType=resumable&name=\(path)"
+        var components = URLComponents(url: request.url!, resolvingAgainstBaseURL: false)
+        if components?.host == "www.googleapis.com",
+           let path = components?.path {
+          components?.percentEncodedPath = "/upload\(path)"
+        }
+        guard let path = self.GCSEscapedString(self.uploadMetadata.path) else {
+          fatalError("Internal error enqueueing a Storage task")
+        }
+        components?.percentEncodedQuery = "uploadType=resumable&name=\(path)"
 
-      request.url = components?.url
+        request.url = components?.url
 
-      guard let contentType = self.uploadMetadata.contentType else {
-        fatalError("Internal error enqueueing a Storage task")
-      }
-      let uploadFetcher = GTMSessionUploadFetcher(
-        request: request,
-        uploadMIMEType: contentType,
-        chunkSize: self.reference.storage.uploadChunkSizeBytes,
-        fetcherService: self.fetcherService
-      )
-      if let uploadData {
-        uploadFetcher.uploadData = uploadData
-        uploadFetcher.comment = "Data UploadTask"
-      } else if let fileURL {
-        uploadFetcher.uploadFileURL = fileURL
-        uploadFetcher.comment = "File UploadTask"
+        guard let contentType = self.uploadMetadata.contentType else {
+          fatalError("Internal error enqueueing a Storage task")
+        }
 
-        if GULAppEnvironmentUtil.isAppExtension() {
-          uploadFetcher.useBackgroundSession = false
+        let uploadFetcher = GTMSessionUploadFetcher(
+          request: request,
+          uploadMIMEType: contentType,
+          chunkSize: self.reference.storage.uploadChunkSizeBytes,
+          fetcherService: fetcherService
+        )
+        if let uploadData {
+          uploadFetcher.uploadData = uploadData
+          uploadFetcher.comment = "Data UploadTask"
+        } else if let fileURL {
+          uploadFetcher.uploadFileURL = fileURL
+          uploadFetcher.comment = "File UploadTask"
+
+          if GULAppEnvironmentUtil.isAppExtension() {
+            uploadFetcher.useBackgroundSession = false
+          }
         }
-      }
-      uploadFetcher.maxRetryInterval = self.reference.storage.maxUploadRetryInterval
+        uploadFetcher.maxRetryInterval = self.reference.storage.maxUploadRetryInterval
 
-      uploadFetcher.sendProgressBlock = { [weak self] (bytesSent: Int64, totalBytesSent: Int64,
-                                                       totalBytesExpectedToSend: Int64) in
-          guard let self = self else { return }
-          self.state = .progress
-          self.progress.completedUnitCount = totalBytesSent
-          self.progress.totalUnitCount = totalBytesExpectedToSend
-          self.metadata = self.uploadMetadata
-          self.fire(for: .progress, snapshot: self.snapshot)
-          self.state = .running
-      }
-      self.uploadFetcher = uploadFetcher
+        uploadFetcher.sendProgressBlock = { [weak self] (bytesSent: Int64, totalBytesSent: Int64,
+                                                         totalBytesExpectedToSend: Int64) in
+            guard let self = self else { return }
+            self.state = .progress
+            self.progress.completedUnitCount = totalBytesSent
+            self.progress.totalUnitCount = totalBytesExpectedToSend
+            self.metadata = self.uploadMetadata
+            self.fire(for: .progress, snapshot: self.snapshot)
+            self.state = .running
+        }
+        self.uploadFetcher = uploadFetcher
 
-      // Process fetches
-      self.state = .running
-      Task {
+        // Process fetches
+        self.state = .running
         do {
           let data = try await self.uploadFetcher?.beginFetch()
           // Fire last progress updates
@@ -208,14 +211,13 @@ import Foundation
   // MARK: - Internal Implementations
 
   init(reference: StorageReference,
-       service: GTMSessionFetcherService,
        queue: DispatchQueue,
        file: URL? = nil,
        data: Data? = nil,
        metadata: StorageMetadata) {
     uploadMetadata = metadata
     uploadData = data
-    super.init(reference: reference, service: service, queue: queue, file: file)
+    super.init(reference: reference, queue: queue, file: file)
 
     if uploadMetadata.contentType == nil {
       uploadMetadata.contentType = StorageUtils.MIMETypeForExtension(file?.pathExtension)
diff --git a/FirebaseStorage/Tests/Unit/StorageComponentTests.swift b/FirebaseStorage/Tests/Unit/StorageComponentTests.swift
index c8c42f949d9..6342a15c590 100644
--- a/FirebaseStorage/Tests/Unit/StorageComponentTests.swift
+++ b/FirebaseStorage/Tests/Unit/StorageComponentTests.swift
@@ -32,14 +32,14 @@ class StorageComponentTests: StorageTestHelpers {
 
   /// Tests that a Storage instance can be created properly.
   func testStorageInstanceCreation() throws {
-    let app = try XCTUnwrap(StorageComponentTests.app)
+    let app = try XCTUnwrap(app)
     let storage1 = Storage.storage(app: app, url: "gs://foo-bar.appspot.com")
     XCTAssertNotNil(storage1)
   }
 
   /// Tests that a Storage instances are reused properly.
   func testMultipleComponentInstancesCreated() throws {
-    let app = try XCTUnwrap(StorageComponentTests.app)
+    let app = try XCTUnwrap(app)
     let storage1 = Storage.storage(app: app, url: "gs://foo-bar.appspot.com")
     let storage2 = Storage.storage(app: app, url: "gs://foo-bar.appspot.com")
 
diff --git a/FirebaseStorage/Tests/Unit/StorageDeleteTests.swift b/FirebaseStorage/Tests/Unit/StorageDeleteTests.swift
index 52484c17fca..1f6a2ed4efd 100644
--- a/FirebaseStorage/Tests/Unit/StorageDeleteTests.swift
+++ b/FirebaseStorage/Tests/Unit/StorageDeleteTests.swift
@@ -56,7 +56,6 @@ class StorageDeleteTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageDeleteTask.deleteTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { _, error in
       expectation.fulfill()
@@ -82,7 +81,6 @@ class StorageDeleteTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageDeleteTask.deleteTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { _, error in
       expectation.fulfill()
@@ -105,7 +103,6 @@ class StorageDeleteTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage, path: path)
     StorageDeleteTask.deleteTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { _, error in
       expectation.fulfill()
@@ -113,54 +110,39 @@ class StorageDeleteTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthenticated() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthenticatedBlock()
+  func testUnsuccessfulFetchUnauthenticated() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthenticatedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageDeleteTask.deleteTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { _, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthenticated.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      try await ref.delete()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthenticated.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthorized() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthorizedBlock()
+  func testUnsuccessfulFetchUnauthorized() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthorizedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageDeleteTask.deleteTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { _, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthorized.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      try await ref.delete()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthorized.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchObjectDoesntExist() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = notFoundBlock()
+  func testUnsuccessfulFetchObjectDoesntExist() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(notFoundBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageDeleteTask.deleteTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { _, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.objectNotFound.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      try await ref.delete()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.objectNotFound.rawValue)
     }
-    waitForExpectation(test: self)
   }
 }
diff --git a/FirebaseStorage/Tests/Unit/StorageGetMetadataTests.swift b/FirebaseStorage/Tests/Unit/StorageGetMetadataTests.swift
index af45994e939..a2428d792fc 100644
--- a/FirebaseStorage/Tests/Unit/StorageGetMetadataTests.swift
+++ b/FirebaseStorage/Tests/Unit/StorageGetMetadataTests.swift
@@ -56,7 +56,6 @@ class StorageGetMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageGetMetadataTask.getMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { metadata, error in
       expectation.fulfill()
@@ -82,7 +81,6 @@ class StorageGetMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageGetMetadataTask.getMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { metadata, error in
       expectation.fulfill()
@@ -105,7 +103,6 @@ class StorageGetMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage, path: path)
     StorageGetMetadataTask.getMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { metadata, error in
       expectation.fulfill()
@@ -113,55 +110,40 @@ class StorageGetMetadataTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthenticated() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthenticatedBlock()
+  func testUnsuccessfulFetchUnauthenticated() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthenticatedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageGetMetadataTask.getMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthenticated.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.getMetadata()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthenticated.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthorized() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthorizedBlock()
+  func testUnsuccessfulFetchUnauthorized() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthorizedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageGetMetadataTask.getMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthorized.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.getMetadata()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthorized.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchObjectDoesntExist() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = notFoundBlock()
+  func testUnsuccessfulFetchObjectDoesntExist() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(notFoundBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageGetMetadataTask.getMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.objectNotFound.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.getMetadata()
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.objectNotFound.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
   func testUnsuccessfulFetchBadJSON() {
@@ -172,7 +154,6 @@ class StorageGetMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageGetMetadataTask.getMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self
     ) { metadata, error in
       XCTAssertNil(metadata)
diff --git a/FirebaseStorage/Tests/Unit/StorageListTests.swift b/FirebaseStorage/Tests/Unit/StorageListTests.swift
index 121a7954292..1b03ee62a18 100644
--- a/FirebaseStorage/Tests/Unit/StorageListTests.swift
+++ b/FirebaseStorage/Tests/Unit/StorageListTests.swift
@@ -108,7 +108,6 @@ class StorageListTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageListTask.listTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       pageSize: nil,
       previousPageToken: nil
@@ -118,25 +117,24 @@ class StorageListTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testDefaultListWithEmulator() {
-    let expectation = self.expectation(description: #function)
+  func testDefaultListWithEmulator() async throws {
     let storage = self.storage()
     storage.useEmulator(withHost: "localhost", port: 8080)
-    fetcherService?.allowLocalhostRequest = true
 
-    fetcherService?.testBlock = { (fetcher: GTMSessionFetcher,
-                                   response: GTMSessionFetcherTestResponse) in
+    let testBlock = { (fetcher: GTMSessionFetcher,
+                       response: GTMSessionFetcherTestResponse) in
         let url = fetcher.request!.url!
         XCTAssertEqual(url.scheme, "http")
         XCTAssertEqual(url.host, "localhost")
         XCTAssertEqual(url.port, 8080)
         XCTAssertEqual(url.path, "/v0/b/bucket/o")
         let queryItems = URLComponents(url: url, resolvingAgainstBaseURL: false)!.queryItems!
-        XCTAssertEqual(queryItems.count, 2)
+        XCTAssertEqual(queryItems.count, 3)
         for item in queryItems {
           switch item.name {
           case "prefix": XCTAssertEqual(item.value, "object/")
           case "delimiter": XCTAssertEqual(item.value, "/")
+          case "maxResults": XCTAssertEqual(item.value, "123")
           default: XCTFail("Unexpected URLComponent Query Item")
           }
         }
@@ -147,20 +145,9 @@ class StorageListTests: StorageTestHelpers {
                                            headerFields: nil)
         response(httpResponse, "{}".data(using: .utf8), nil)
     }
-
-    let path = objectPath()
-    let ref = StorageReference(storage: storage, path: path)
-    StorageListTask.listTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      pageSize: nil,
-      previousPageToken: nil
-    ) { result, error in
-      XCTAssertNil(error)
-      expectation.fulfill()
-    }
-    waitForExpectation(test: self)
+    await storage.fetcherService.updateTestBlock(testBlock)
+    let ref = storage.reference(withPath: "object")
+    let _ = try await ref.list(maxResults: 123)
   }
 
   func testListWithPageSizeAndPageToken() {
@@ -196,7 +183,6 @@ class StorageListTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageListTask.listTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       pageSize: 42,
       previousPageToken: "foo"
@@ -237,7 +223,6 @@ class StorageListTests: StorageTestHelpers {
     let ref = storage.reference(withPath: "+foo")
     StorageListTask.listTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       pageSize: nil,
       previousPageToken: nil
@@ -247,9 +232,7 @@ class StorageListTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testListWithResponse() throws {
-    let expectation = self.expectation(description: #function)
-
+  func testListWithResponse() async throws {
     let jsonString = "{\n" +
       "  \"prefixes\": [\n" +
       "    \"object/prefixWithoutSlash\",\n" +
@@ -267,11 +250,10 @@ class StorageListTests: StorageTestHelpers {
       "  ],\n" +
       "  \"nextPageToken\": \"foo\"" +
       "}"
-
     let responseData = try XCTUnwrap(jsonString.data(using: .utf8))
 
-    fetcherService?.testBlock = { (fetcher: GTMSessionFetcher,
-                                   response: GTMSessionFetcherTestResponse) in
+    let testBlock = { (fetcher: GTMSessionFetcher,
+                       response: GTMSessionFetcherTestResponse) in
         let httpResponse = HTTPURLResponse(url: (fetcher.request?.url)!,
                                            statusCode: 200,
                                            httpVersion: "HTTP/1.1",
@@ -280,36 +262,22 @@ class StorageListTests: StorageTestHelpers {
     }
 
     let storage = storage()
+    await storage.fetcherService.updateTestBlock(testBlock)
     let ref = storage.reference(withPath: "object")
-    StorageListTask.listTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      pageSize: nil,
-      previousPageToken: nil
-    ) { result, error in
-      XCTAssertNotNil(result)
-      XCTAssertNil(error)
-
-      XCTAssertEqual(result?.items, [ref.child("data1.dat"), ref.child("data2.dat")])
-      XCTAssertEqual(
-        result?.prefixes,
-        [ref.child("prefixWithoutSlash"), ref.child("prefixWithSlash")]
-      )
-      XCTAssertEqual(result?.pageToken, "foo")
-
-      expectation.fulfill()
-    }
-    waitForExpectation(test: self)
+    let result = try await ref.list(maxResults: 1000)
+    XCTAssertEqual(result.items, [ref.child("data1.dat"), ref.child("data2.dat")])
+    XCTAssertEqual(
+      result.prefixes,
+      [ref.child("prefixWithoutSlash"), ref.child("prefixWithSlash")]
+    )
+    XCTAssertEqual(result.pageToken, "foo")
   }
 
-  func testListWithErrorResponse() throws {
-    let expectation = self.expectation(description: #function)
-
+  func testListWithErrorResponse() async {
     let error = NSError(domain: "com.google.firebase.storage", code: 404)
 
-    fetcherService?.testBlock = { (fetcher: GTMSessionFetcher,
-                                   response: GTMSessionFetcherTestResponse) in
+    let testBlock = { (fetcher: GTMSessionFetcher,
+                       response: GTMSessionFetcherTestResponse) in
         let httpResponse = HTTPURLResponse(url: (fetcher.request?.url)!,
                                            statusCode: 403,
                                            httpVersion: "HTTP/1.1",
@@ -318,20 +286,13 @@ class StorageListTests: StorageTestHelpers {
     }
 
     let storage = storage()
+    await storage.fetcherService.updateTestBlock(testBlock)
     let ref = storage.reference(withPath: "object")
-    StorageListTask.listTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      pageSize: nil,
-      previousPageToken: nil
-    ) { result, error in
-      XCTAssertNotNil(error)
-      XCTAssertNil(result)
-      XCTAssertEqual((error as? NSError)!.domain, "FIRStorageErrorDomain")
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.objectNotFound.rawValue)
-      expectation.fulfill()
+    do {
+      let _ = try await ref.list(maxResults: 1000)
+    } catch {
+      XCTAssertEqual((error as NSError).domain, "FIRStorageErrorDomain")
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.objectNotFound.rawValue)
     }
-    waitForExpectation(test: self)
   }
 }
diff --git a/FirebaseStorage/Tests/Unit/StorageTestHelpers.swift b/FirebaseStorage/Tests/Unit/StorageTestHelpers.swift
index 97f2838bfe0..9e1cfeb2951 100644
--- a/FirebaseStorage/Tests/Unit/StorageTestHelpers.swift
+++ b/FirebaseStorage/Tests/Unit/StorageTestHelpers.swift
@@ -22,20 +22,23 @@ import XCTest
 
 @available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
 class StorageTestHelpers: XCTestCase {
-  static var app: FirebaseApp!
+  var app: FirebaseApp!
 
+  static var uniqueApp = 0
   func storage() -> Storage {
-    return Storage(app: FirebaseApp.app()!, bucket: "bucket")
+    return Storage(app: app, bucket: "bucket")
   }
 
-  override class func setUp() {
+  override func setUp() {
     super.setUp()
     if app == nil {
       let options = FirebaseOptions(googleAppID: "0:0000000000000:ios:0000000000000000",
                                     gcmSenderID: "00000000000000000-00000000000-000000000")
       options.projectID = "myProjectID"
-      FirebaseApp.configure(options: options)
-      app = FirebaseApp(instanceWithName: "test", options: options)
+      StorageTestHelpers.uniqueApp += 1
+      let appName = "test\(StorageTestHelpers.uniqueApp)"
+      FirebaseApp.configure(name: appName, options: options)
+      app = FirebaseApp.app(name: appName)
     }
   }
 
diff --git a/FirebaseStorage/Tests/Unit/StorageUpdateMetadataTests.swift b/FirebaseStorage/Tests/Unit/StorageUpdateMetadataTests.swift
index eb08980d84d..7650032d179 100644
--- a/FirebaseStorage/Tests/Unit/StorageUpdateMetadataTests.swift
+++ b/FirebaseStorage/Tests/Unit/StorageUpdateMetadataTests.swift
@@ -21,7 +21,7 @@ import XCTest
 class StorageUpdateMetadataTests: StorageTestHelpers {
   var fetcherService: GTMSessionFetcherService?
   var dispatchQueue: DispatchQueue?
-  var metadata: StorageMetadata?
+  var metadata: StorageMetadata!
 
   override func setUp() {
     super.setUp()
@@ -53,7 +53,6 @@ class StorageUpdateMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageUpdateMetadataTask.updateMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       metadata: metadata!
     ) { metadata, error in
@@ -62,23 +61,14 @@ class StorageUpdateMetadataTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testSuccessfulFetch() {
-    let expectation = self.expectation(description: #function)
-    fetcherService!.testBlock = successBlock(withMetadata: metadata)
+  func testSuccessfulFetch() async throws {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(successBlock(withMetadata: metadata))
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageUpdateMetadataTask.updateMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      metadata: metadata!
-    ) { metadata, error in
-      XCTAssertNil(error)
-      XCTAssertEqual(self.metadata?.bucket, metadata?.bucket)
-      XCTAssertEqual(self.metadata?.name, metadata?.name)
-      expectation.fulfill()
-    }
-    waitForExpectation(test: self)
+    let ref = StorageReference(storage: storage, path: path)
+    let metadata = try await ref.updateMetadata(metadata)
+    XCTAssertEqual(self.metadata?.bucket, metadata.bucket)
+    XCTAssertEqual(self.metadata?.name, metadata.name)
   }
 
   func testSuccessfulFetchWithEmulator() {
@@ -96,7 +86,6 @@ class StorageUpdateMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage, path: path)
     StorageUpdateMetadataTask.updateMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       metadata: metadata!
     ) { metadata, error in
@@ -105,58 +94,40 @@ class StorageUpdateMetadataTests: StorageTestHelpers {
     waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthenticated() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthenticatedBlock()
+  func testUnsuccessfulFetchUnauthenticated() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthenticatedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageUpdateMetadataTask.updateMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      metadata: metadata!
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthenticated.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.updateMetadata(metadata)
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthenticated.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchUnauthorized() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = unauthorizedBlock()
+  func testUnsuccessfulFetchUnauthorized() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(unauthorizedBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageUpdateMetadataTask.updateMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      metadata: metadata!
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.unauthorized.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.updateMetadata(metadata)
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.unauthorized.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
-  func testUnsuccessfulFetchObjectDoesntExist() {
-    let expectation = self.expectation(description: #function)
-
-    fetcherService!.testBlock = notFoundBlock()
+  func testUnsuccessfulFetchObjectDoesntExist() async {
+    let storage = storage()
+    await storage.fetcherService.updateTestBlock(notFoundBlock())
     let path = objectPath()
-    let ref = StorageReference(storage: storage(), path: path)
-    StorageUpdateMetadataTask.updateMetadataTask(
-      reference: ref,
-      fetcherService: fetcherService!.self,
-      queue: dispatchQueue!.self,
-      metadata: metadata!
-    ) { metadata, error in
-      XCTAssertEqual((error as? NSError)!.code, StorageErrorCode.objectNotFound.rawValue)
-      expectation.fulfill()
+    let ref = StorageReference(storage: storage, path: path)
+    do {
+      let _ = try await ref.updateMetadata(metadata)
+    } catch {
+      XCTAssertEqual((error as NSError).code, StorageErrorCode.objectNotFound.rawValue)
     }
-    waitForExpectation(test: self)
   }
 
   func testUnsuccessfulFetchBadJSON() {
@@ -167,7 +138,6 @@ class StorageUpdateMetadataTests: StorageTestHelpers {
     let ref = StorageReference(storage: storage(), path: path)
     StorageUpdateMetadataTask.updateMetadataTask(
       reference: ref,
-      fetcherService: fetcherService!.self,
       queue: dispatchQueue!.self,
       metadata: metadata!
     ) { metadata, error in


Test patch: