[auth-swift] Swift AuthDispatcher, two fakes, one test (#10903)

Author: paulb777

FirebaseAuth/Sources/Auth/FIRAuth.m

@@ -31,7 +31,6 @@
 #import "FirebaseAuth-Swift.h"
 #import "FirebaseAppCheck/Interop/FIRAppCheckInterop.h"
 #import "FirebaseAuth/Sources/Auth/FIRAuthDataResult_Internal.h"
-#import "FirebaseAuth/Sources/Auth/FIRAuthDispatcher.h"
 #import "FirebaseAuth/Sources/Auth/FIRAuthGlobalWorkQueue.h"
 #import "FirebaseAuth/Sources/SystemService/FIRAuthStoredUserManager.h"
 #import "FirebaseAuth/Sources/User/FIRUser_Internal.h"

FirebaseAuth/Sources/Auth/FIRAuthDispatcher.h

@@ -0,0 +1,47 @@
+// Copyright 2023 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
+
+// TODO: Get rid of public's and @objc's once FirebaseAuth.m is in Swift.
+
+/** @class AuthDispatcher
+    @brief A utility class used to facilitate scheduling tasks to be executed in the future.
+ */
+@objc(FIRAuthDispatcher) public class AuthDispatcher: NSObject {
+  @objc(sharedInstance) public static let shared = AuthDispatcher()
+
+  /** @property dispatchAfterImplementation
+      @brief Allows custom implementation of dispatchAfterDelay:queue:callback:.
+      @remarks Set to nil to restore default implementation.
+   */
+  @objc public
+  var dispatchAfterImplementation: ((TimeInterval, DispatchQueue, @escaping () -> Void) -> Void)?
+
+  /** @fn dispatchAfterDelay:queue:callback:
+      @brief Schedules task in the future after a specified delay.
+
+      @param delay The delay in seconds after which the task will be scheduled to execute.
+      @param queue The dispatch queue on which the task will be submitted.
+      @param task The task (block) to be scheduled for future execution.
+   */
+  @objc public
+  func dispatch(afterDelay delay: TimeInterval, queue: DispatchQueue, task: @escaping () -> Void) {
+    if let dispatchAfterImplementation {
+      dispatchAfterImplementation(delay, queue, task)
+    } else {
+      queue.asyncAfter(deadline: DispatchTime.now() + delay, execute: task)
+    }
+  }
+}