Initial service implementation for using a PIN code. (#1912)

* Initial service implementation for using a PIN code.

* Tweak Danger for commit size

600-800 lines is perfectly normal for our PRs, up it to 1000.

UnitTests/Sources/AppLock/AppLockScreenViewModelTests.swift

@@ -0,0 +1,49 @@
+//
+// Copyright 2022 New Vector Ltd
+//
+// 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 XCTest
+
+@testable import ElementX
+
+@MainActor
+class AppLockScreenViewModelTests: XCTestCase {
+    var appLockService: AppLockService!
+    var keychainController: KeychainControllerMock!
+    var viewModel: AppLockScreenViewModelProtocol!
+    
+    var context: AppLockScreenViewModelType.Context { viewModel.context }
+    
+    override func setUp() {
+        AppSettings.reset()
+        keychainController = KeychainControllerMock()
+        appLockService = AppLockService(keychainController: keychainController, appSettings: AppSettings())
+        viewModel = AppLockScreenViewModel(appLockService: appLockService)
+    }
+    
+    func testUnlock() async throws {
+        // Given a valid PIN code.
+        let pinCode = "2023"
+        keychainController.pinCodeReturnValue = pinCode
+        
+        // When entering it on the lock screen.
+        let deferred = deferFulfillment(viewModel.actions) { $0 == .appUnlocked }
+        context.send(viewAction: .submitPINCode(pinCode))
+        let result = try await deferred.fulfill()
+        
+        // The app should become unlocked.
+        XCTAssertEqual(result, .appUnlocked)
+    }
+}

UnitTests/Sources/AppLock/AppLockServiceTests.swift

@@ -0,0 +1,178 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// 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 XCTest
+
+@testable import ElementX
+
+@MainActor
+class AppLockServiceTests: XCTestCase {
+    var appSettings: AppSettings!
+    var service: AppLockService!
+    
+    override func setUp() {
+        AppSettings.reset()
+        appSettings = AppSettings()
+        appSettings.appLockFlowEnabled = true
+        
+        let keychainController = KeychainController(service: .tests, accessGroup: InfoPlistReader.main.keychainAccessGroupIdentifier)
+        
+        service = AppLockService(keychainController: keychainController, appSettings: appSettings)
+        service.disable()
+    }
+    
+    override func tearDown() {
+        AppSettings.reset()
+    }
+    
+    func testValidPINCode() {
+        // Given a service that hasn't been enabled.
+        XCTAssertFalse(service.isEnabled, "The service shouldn't be enabled to begin with.")
+        
+        // When setting a PIN code.
+        let pinCode = "2023" // Highly secure PIN that is rotated every 12 months.
+        guard case .success = service.setupPINCode(pinCode) else {
+            XCTFail("The PIN should be valid.")
+            return
+        }
+        
+        // Then service should be enabled and only the provided PIN should work to unlock the app.
+        XCTAssertTrue(service.isEnabled, "The service should become enabled when setting a PIN.")
+        XCTAssertTrue(service.unlock(with: pinCode), "The provided PIN code should work.")
+        XCTAssertFalse(service.unlock(with: "2024"), "No other PIN code should work.")
+        XCTAssertFalse(service.unlock(with: "1234"), "No other PIN code should work.")
+        XCTAssertFalse(service.unlock(with: "9999"), "No other PIN code should work.")
+    }
+    
+    func testWeakPINCode() {
+        // Given a service that hasn't been enabled.
+        XCTAssertFalse(service.isEnabled, "The service shouldn't be enabled to begin with.")
+        
+        // When setting a PIN code that is in the block list.
+        let pinCode = appSettings.appLockPINCodeBlockList[0]
+        let result = service.setupPINCode(pinCode)
+        
+        // Then the setup should fail and the service be left as disabled.
+        guard case let .failure(error) = result else {
+            XCTFail("The call should have failed.")
+            return
+        }
+        XCTAssertEqual(error, .weakPIN, "The PIN should be rejected as weak.")
+        XCTAssertFalse(service.isEnabled, "The service should remain disabled.")
+    }
+    
+    func testShortPINCode() {
+        // Given a service that hasn't been enabled.
+        XCTAssertFalse(service.isEnabled, "The service shouldn't be enabled to begin with.")
+        
+        // When setting a PIN code that is too short
+        let pinCode = "123"
+        let result = service.setupPINCode(pinCode)
+        
+        // Then the setup should fail and the service be left as disabled.
+        guard case let .failure(error) = result else {
+            XCTFail("The call should have failed.")
+            return
+        }
+        XCTAssertEqual(error, .invalidPIN, "The PIN should be rejected as invalid.")
+        XCTAssertFalse(service.isEnabled, "The service should remain disabled.")
+    }
+    
+    func testNonNumericPINCode() {
+        // Given a service that hasn't been enabled.
+        XCTAssertFalse(service.isEnabled, "The service shouldn't be enabled to begin with.")
+        
+        // When setting a PIN code that is too short
+        let pinCode = "abcd"
+        let result = service.setupPINCode(pinCode)
+        
+        // Then the setup should fail and the service be left as disabled.
+        guard case let .failure(error) = result else {
+            XCTFail("The call should have failed.")
+            return
+        }
+        XCTAssertEqual(error, .invalidPIN, "The PIN should be rejected as invalid.")
+        XCTAssertFalse(service.isEnabled, "The service should remain disabled.")
+    }
+    
+    func testChangePINCode() {
+        // Given a service that is already enabled with a PIN.
+        let pinCode = "2023"
+        let newPINCode = "2024"
+        guard case .success = service.setupPINCode(pinCode) else {
+            XCTFail("The PIN should be valid.")
+            return
+        }
+        XCTAssertTrue(service.isEnabled, "The service should be enabled.")
+        XCTAssertTrue(service.unlock(with: pinCode), "The initial PIN should work.")
+        XCTAssertFalse(service.unlock(with: newPINCode), "The PIN we're about to set should not work.")
+        
+        // When updating the PIN code.
+        guard case .success = service.setupPINCode(newPINCode) else {
+            XCTFail("The PIN should be valid.")
+            return
+        }
+        
+        // Then the old code should not be accepted.
+        XCTAssertTrue(service.isEnabled, "The service should remain enabled.")
+        XCTAssertTrue(service.unlock(with: newPINCode), "The new PIN should work.")
+        XCTAssertFalse(service.unlock(with: pinCode), "The original PIN should be rejected.")
+    }
+    
+    func testInvalidChangePINCode() {
+        // Given a service that is already enabled with a PIN.
+        let pinCode = "2023"
+        let invalidPIN = appSettings.appLockPINCodeBlockList[0]
+        guard case .success = service.setupPINCode(pinCode) else {
+            XCTFail("The PIN should be valid.")
+            return
+        }
+        XCTAssertTrue(service.isEnabled, "The service should be enabled.")
+        XCTAssertTrue(service.unlock(with: pinCode), "The initial PIN should work.")
+        XCTAssertFalse(service.unlock(with: invalidPIN), "The PIN we're about to set should not work.")
+        
+        // When updating the PIN code that is in the block list.
+        let result = service.setupPINCode(invalidPIN)
+        
+        // Then it should fail and nothing should change.
+        guard case let .failure(error) = result else {
+            XCTFail("The call should have failed.")
+            return
+        }
+        XCTAssertEqual(error, .weakPIN, "The PIN should be rejected as weak.")
+        XCTAssertTrue(service.isEnabled, "The service should remain enabled.")
+        XCTAssertFalse(service.unlock(with: invalidPIN), "The rejected PIN shouldn't work.")
+        XCTAssertTrue(service.unlock(with: pinCode), "The original PIN should continue to work.")
+    }
+    
+    func testDisablePINCode() {
+        // Given a service that is already enabled with a PIN.
+        let pinCode = "2023"
+        guard case .success = service.setupPINCode(pinCode) else {
+            XCTFail("The PIN should be valid.")
+            return
+        }
+        XCTAssertTrue(service.isEnabled, "The service should be enabled.")
+        XCTAssertTrue(service.unlock(with: pinCode), "The initial PIN should work.")
+        
+        // When disabling the PIN code.
+        service.disable()
+        
+        // Then the PIN code should be removed.
+        XCTAssertFalse(service.isEnabled, "The service should no longer be enabled.")
+        XCTAssertFalse(service.unlock(with: pinCode), "The initial PIN shouldn't work any more.")
+    }
+}

UnitTests/Sources/AppLock/AppLockTimerTests.swift

@@ -0,0 +1,154 @@
+//
+// Copyright 2023 New Vector Ltd
+//
+// 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 XCTest
+
+@testable import ElementX
+
+class AppLockTimerTests: XCTestCase {
+    var timer: AppLockTimer!
+    
+    let now = Date.now
+    
+    var gracePeriod: TimeInterval { timer.gracePeriod }
+    var halfGracePeriod: TimeInterval { gracePeriod / 2 }
+    var gracePeriodX2: TimeInterval { gracePeriod * 2 }
+    var gracePeriodX10: TimeInterval { gracePeriod * 10 }
+    
+    override func tearDown() {
+        timer = nil
+    }
+    
+    func testTimerLockedOnStartup() {
+        setupTimer(unlocked: false)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now),
+                      "The app should be locked on a fresh launch.")
+        
+        setupTimer(unlocked: false)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + 1),
+                      "The app should be locked after a fresh launch.")
+        
+        setupTimer(unlocked: false)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + halfGracePeriod),
+                      "The app should be locked after a fresh launch.")
+        
+        setupTimer(unlocked: false)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriod),
+                      "The app should be locked after a fresh launch.")
+        
+        setupTimer(unlocked: false)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriodX10),
+                      "The app should be locked after a fresh launch.")
+    }
+    
+    func testTimerBeforeFirstUnlock() {
+        setupTimer(unlocked: false, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now),
+                      "The app should always remain locked after backgrounding when locked.")
+        
+        setupTimer(unlocked: false, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + 1),
+                      "The app should always remain locked after backgrounding when locked.")
+        
+        setupTimer(unlocked: false, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + halfGracePeriod),
+                      "The app should always remain locked after backgrounding when locked.")
+        
+        setupTimer(unlocked: false, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriod),
+                      "The app should always remain locked after backgrounding when locked.")
+        
+        setupTimer(unlocked: false, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriodX10),
+                      "The app should always remain locked after backgrounding when locked.")
+    }
+    
+    func testTimerWhenUnlocked() {
+        setupTimer(unlocked: true, backgroundedAt: now)
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: now + 1),
+                       "The app should remain unlocked when it was unlocked and backgrounded for less then the grace period.")
+        
+        setupTimer(unlocked: true, backgroundedAt: now)
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: now + halfGracePeriod),
+                       "The app should remain unlocked when it was unlocked and backgrounded for less then the grace period.")
+        
+        setupTimer(unlocked: true, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriod),
+                      "The app should become locked when it was unlocked and backgrounded for more than the grace period.")
+        
+        setupTimer(unlocked: true, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now + gracePeriodX10),
+                      "The app should become locked when it was unlocked and backgrounded for more than the grace period.")
+    }
+    
+    func testTimerRepeatingWithinGracePeriod() {
+        setupTimer(unlocked: true, backgroundedAt: now)
+        
+        var nextCheck = now + halfGracePeriod
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: nextCheck),
+                       "The app should remain unlocked when it was unlocked and backgrounded for less then the grace period.")
+        timer.applicationDidEnterBackground(date: nextCheck)
+        
+        nextCheck = now + gracePeriod
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: nextCheck),
+                       "The app should remain unlocked when repeating the backgrounded and foreground within the grace period.")
+        timer.applicationDidEnterBackground(date: nextCheck)
+        
+        nextCheck = now + gracePeriod + halfGracePeriod
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: nextCheck),
+                       "The app should remain unlocked when repeating the backgrounded and foreground within the grace period.")
+        timer.applicationDidEnterBackground(date: nextCheck)
+        
+        nextCheck = now + gracePeriodX2
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: nextCheck),
+                       "The app should remain unlocked when repeating the backgrounded and foreground within the grace period.")
+        timer.applicationDidEnterBackground(date: nextCheck)
+        
+        nextCheck = now + gracePeriodX10
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: nextCheck),
+                      "The app should become locked however when finally staying backgrounded for longer than the grace period.")
+    }
+    
+    func testTimerWithLongForeground() {
+        setupTimer(unlocked: true)
+        
+        let backgroundDate = now + gracePeriodX10
+        timer.applicationDidEnterBackground(date: backgroundDate)
+        
+        XCTAssertFalse(timer.computeLockState(willEnterForegroundAt: backgroundDate + 1),
+                       "The grace period should be measured from the time the app was backgrounded, and not when it was unlocked.")
+    }
+    
+    func testChangingTimeLocksApp() {
+        setupTimer(unlocked: true, backgroundedAt: now)
+        XCTAssertTrue(timer.computeLockState(willEnterForegroundAt: now - 1),
+                      "The the device's clock is changed to before the app was backgrounded, the device should remain locked.")
+    }
+    
+    /// Sets up the timer for testing.
+    /// - Parameters:
+    ///   - unlocked: Whether the timer should consider itself unlocked or not.
+    ///   - backgroundedDate: If not nil, the timer will consider the app to have been backgrounded at the specified date.
+    private func setupTimer(unlocked: Bool, backgroundedAt backgroundedDate: Date? = nil) {
+        timer = AppLockTimer(gracePeriod: 180)
+        if unlocked {
+            timer.registerUnlock()
+        }
+        if let backgroundedDate {
+            timer.applicationDidEnterBackground(date: backgroundedDate)
+        }
+    }
+}