Add MessengerStopBackup function

Sources/XXMessengerClient/Messenger/Functions/MessengerStopBackup.swift

+import Bindings
+import XCTestDynamicOverlay
+
+public struct MessengerStopBackup {
+  public var run: () throws -> Void
+
+  public func callAsFunction() throws {
+    try run()
+  }
+}
+
+extension MessengerStopBackup {
+  public static func live(_ env: MessengerEnvironment) -> MessengerStopBackup {
+    MessengerStopBackup {
+      guard let backup = env.backup() else { return }
+      try backup.stop()
+      env.backup.set(nil)
+    }
+  }
+}
+
+extension MessengerStopBackup {
+  public static let unimplemented = MessengerStopBackup(
+    run: XCTUnimplemented("\(Self.self)")
+  )
+}

Sources/XXMessengerClient/Messenger/Messenger.swift

@@ -31,6 +31,7 @@ public struct Messenger {
   public var sendMessage: MessengerSendMessage
   public var registerBackupCallback: MessengerRegisterBackupCallback
   public var isBackupRunning: MessengerIsBackupRunning
+  public var stopBackup: MessengerStopBackup
 }
 
 extension Messenger {
@@ -65,7 +66,8 @@ extension Messenger {
       verifyContact: .live(env),
       sendMessage: .live(env),
       registerBackupCallback: .live(env),
-      isBackupRunning: .live(env)
+      isBackupRunning: .live(env),
+      stopBackup: .live(env)
     )
   }
 }
@@ -101,6 +103,7 @@ extension Messenger {
     verifyContact: .unimplemented,
     sendMessage: .unimplemented,
     registerBackupCallback: .unimplemented,
-    isBackupRunning: .unimplemented
+    isBackupRunning: .unimplemented,
+    stopBackup: .unimplemented
   )
 }

Tests/XXMessengerClientTests/Messenger/Functions/MessengerStopBackupTests.swift

+import CustomDump
+import XCTest
+import XXClient
+@testable import XXMessengerClient
+
+final class MessengerStopBackupTests: XCTestCase {
+  func testStop() throws {
+    var didStopBackup = 0
+    var didSetBackup: [Backup?] = []
+
+    var env: MessengerEnvironment = .unimplemented
+    env.backup.get = {
+      var backup: Backup = .unimplemented
+      backup.stop.run = { didStopBackup += 1 }
+      return backup
+    }
+    env.backup.set = { backup in
+      didSetBackup.append(backup)
+    }
+    let stop: MessengerStopBackup = .live(env)
+
+    try stop()
+
+    XCTAssertEqual(didStopBackup, 1)
+    XCTAssertEqual(didSetBackup.count, 1)
+    XCTAssertNil(didSetBackup.first as? Backup)
+  }
+
+  func testStopFailure() {
+    struct Failure: Error, Equatable {}
+    let failure = Failure()
+
+    var env: MessengerEnvironment = .unimplemented
+    env.backup.get = {
+      var backup: Backup = .unimplemented
+      backup.stop.run = { throw failure }
+      return backup
+    }
+    let stop: MessengerStopBackup = .live(env)
+
+    XCTAssertThrowsError(try stop()) { error in
+      XCTAssertNoDifference(error as NSError, failure as NSError)
+    }
+  }
+
+  func testStopWithoutBackup() throws {
+    var env: MessengerEnvironment = .unimplemented
+    env.backup.get = { nil }
+    let stop: MessengerStopBackup = .live(env)
+
+    try stop()
+  }
+}