From 5a729d9f7e577211d5abcc48deb976396ad9e345 Mon Sep 17 00:00:00 2001
From: Dariusz Rybicki <dariusz@elixxir.io>
Date: Thu, 29 Sep 2022 15:04:13 +0200
Subject: [PATCH] Add BackupStorage utility
---
.../Utils/BackupStorage.swift | 66 +++++++++++++++++
.../Utils/BackupStorageTests.swift | 70 +++++++++++++++++++
2 files changed, 136 insertions(+)
create mode 100644 Sources/XXMessengerClient/Utils/BackupStorage.swift
create mode 100644 Tests/XXMessengerClientTests/Utils/BackupStorageTests.swift
diff --git a/Sources/XXMessengerClient/Utils/BackupStorage.swift b/Sources/XXMessengerClient/Utils/BackupStorage.swift
new file mode 100644
index 00000000..b13c86cb
--- /dev/null
+++ b/Sources/XXMessengerClient/Utils/BackupStorage.swift
@@ -0,0 +1,66 @@
+import Foundation
+import XCTestDynamicOverlay
+import XXClient
+
+public struct BackupStorage {
+ public struct Backup: Equatable {
+ public init(
+ date: Date,
+ data: Data
+ ) {
+ self.date = date
+ self.data = data
+ }
+
+ public var date: Date
+ public var data: Data
+ }
+
+ public typealias Observer = (Backup?) -> Void
+
+ public var store: (Data) -> Void
+ public var observe: (@escaping Observer) -> Cancellable
+ public var remove: () -> Void
+}
+
+extension BackupStorage {
+ public static func live(
+ now: @escaping () -> Date
+ ) -> BackupStorage {
+ var observers: [UUID: Observer] = [:]
+ var backup: Backup?
+ func notifyObservers() {
+ observers.values.forEach { $0(backup) }
+ }
+
+ return BackupStorage(
+ store: { data in
+ backup = Backup(
+ date: now(),
+ data: data
+ )
+ notifyObservers()
+ },
+ observe: { observer in
+ let id = UUID()
+ observers[id] = observer
+ defer { observers[id]?(backup) }
+ return Cancellable {
+ observers[id] = nil
+ }
+ },
+ remove: {
+ backup = nil
+ notifyObservers()
+ }
+ )
+ }
+}
+
+extension BackupStorage {
+ public static let unimplemented = BackupStorage(
+ store: XCTUnimplemented("\(Self.self).store"),
+ observe: XCTUnimplemented("\(Self.self).observe", placeholder: Cancellable {}),
+ remove: XCTUnimplemented("\(Self.self).remove")
+ )
+}
diff --git a/Tests/XXMessengerClientTests/Utils/BackupStorageTests.swift b/Tests/XXMessengerClientTests/Utils/BackupStorageTests.swift
new file mode 100644
index 00000000..3dc8272e
--- /dev/null
+++ b/Tests/XXMessengerClientTests/Utils/BackupStorageTests.swift
@@ -0,0 +1,70 @@
+import CustomDump
+import XCTest
+@testable import XXMessengerClient
+
+final class BackupStorageTests: XCTestCase {
+ func testStorage() {
+ var now: Date = .init(0)
+ let storage: BackupStorage = .live(
+ now: { now }
+ )
+
+ var didObserveA: [BackupStorage.Backup?] = []
+ let observerA = storage.observe { backup in
+ didObserveA.append(backup)
+ }
+
+ XCTAssertNoDifference(didObserveA, [nil])
+
+ now = .init(1)
+ didObserveA = []
+ let data1 = "data-1".data(using: .utf8)!
+ storage.store(data1)
+
+ XCTAssertNoDifference(didObserveA, [.init(date: .init(1), data: data1)])
+
+ now = .init(2)
+ didObserveA = []
+ var didObserveB: [BackupStorage.Backup?] = []
+ let observerB = storage.observe { backup in
+ didObserveB.append(backup)
+ }
+
+ XCTAssertNoDifference(didObserveA, [])
+ XCTAssertNoDifference(didObserveB, [.init(date: .init(1), data: data1)])
+
+ now = .init(3)
+ didObserveA = []
+ didObserveB = []
+ let data2 = "data-2".data(using: .utf8)!
+ storage.store(data2)
+
+ XCTAssertNoDifference(didObserveA, [.init(date: .init(3), data: data2)])
+ XCTAssertNoDifference(didObserveB, [.init(date: .init(3), data: data2)])
+
+ now = .init(4)
+ didObserveA = []
+ didObserveB = []
+ observerA.cancel()
+ storage.remove()
+
+ XCTAssertNoDifference(didObserveA, [])
+ XCTAssertNoDifference(didObserveB, [nil])
+
+ now = .init(5)
+ didObserveA = []
+ didObserveB = []
+ observerB.cancel()
+ let data3 = "data-3".data(using: .utf8)!
+ storage.store(data3)
+
+ XCTAssertNoDifference(didObserveA, [])
+ XCTAssertNoDifference(didObserveB, [])
+ }
+}
+
+private extension Date {
+ init(_ timeIntervalSince1970: TimeInterval) {
+ self.init(timeIntervalSince1970: timeIntervalSince1970)
+ }
+}
--
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