Background 0xdead10cc crash fix
This commit fixes the background crashes with termination code 0xdead10cc. Those crashes were caused by the fact that NostrDB was being stored on the shared app container (Because our app extensions need NostrDB data), and iOS kills any process that holds a file lock after the process is backgrounded. Other developers in the field have run into similar problems in the past (with shared SQLite databases or shared SwiftData), and they generally recommend not to place those database in shared containers at all, mentioning that 0xdead10cc crashes are almost inevitable otherwise: - https://ryanashcraft.com/sqlite-databases-in-app-group-containers/ - https://inessential.com/2020/02/13/how_we_fixed_the_dreaded_0xdead10cc_cras.html Since iOS aggressively backgrounds and terminates processes with tight timing constraints that are mostly outside our control (despite using Apple's recommended mechanisms, such as requesting more time to perform closing operations), this fix aims to address the issue by a different storage architecture. Instead of keeping NostrDB data on the shared app container and handling the closure/opening of the database with the app lifecycle signals, keep the main NostrDB database file in the app's private container, and instead take periodic read-only snapshots of NostrDB in the shared container, so as to allow extensions to have recent NostrDB data without all the complexities of keeping the main file in the shared container. This does have the tradeoff that more storage will be used by NostrDB due to file duplication, but that can be mitigated via other techniques if necessary. Closes: https://github.com/damus-io/damus/issues/2638 Closes: https://github.com/damus-io/damus/issues/3463 Changelog-Fixed: Fixed background crashes with error code 0xdead10cc Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
This commit is contained in:
Daniel D’Aquino
325
damusTests/DatabaseSnapshotManagerTests.swift
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325
damusTests/DatabaseSnapshotManagerTests.swift
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//
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// DatabaseSnapshotManagerTests.swift
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// damus
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//
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// Created by Daniel D'Aquino on 2026-01-02.
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//
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import XCTest
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@testable import damus
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final class DatabaseSnapshotManagerTests: XCTestCase {
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var tempDirectory: URL!
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var manager: DatabaseSnapshotManager!
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var testNdb: Ndb!
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override func setUp() async throws {
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try await super.setUp()
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// Create a temporary directory for test files
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tempDirectory = FileManager.default.temporaryDirectory
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.appendingPathComponent(UUID().uuidString, conformingTo: .directory)
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try FileManager.default.createDirectory(at: tempDirectory, withIntermediateDirectories: true)
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self.testNdb = Ndb(path: test_ndb_dir(), owns_db_file: true)!
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// Create the manager
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manager = DatabaseSnapshotManager(ndb: self.testNdb)
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// Clear UserDefaults for consistent testing
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UserDefaults.standard.removeObject(forKey: "lastDatabaseSnapshotDate")
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}
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override func tearDown() async throws {
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// Clean up temporary directory
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if let tempDirectory = tempDirectory {
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try? FileManager.default.removeItem(at: tempDirectory)
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}
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// Clear UserDefaults
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UserDefaults.standard.removeObject(forKey: "lastDatabaseSnapshotDate")
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// Stop any running snapshots
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await manager.stopPeriodicSnapshots()
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manager = nil
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tempDirectory = nil
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try await super.tearDown()
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}
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// MARK: - Snapshot Creation Tests
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func testCreateSnapshotIfNeeded_CreatesSnapshotWhenNeverCreatedBefore() async throws {
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// Given: No previous snapshot exists
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XCTAssertNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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// When: createSnapshotIfNeeded is called
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try await manager.createSnapshotIfNeeded()
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// Then: A snapshot should be created
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XCTAssertNotNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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}
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func testCreateSnapshotIfNeeded_SkipsSnapshotWhenRecentSnapshotExists() async throws {
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// Given: A recent snapshot was just created
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UserDefaults.standard.set(Date(), forKey: "lastDatabaseSnapshotDate")
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// When: createSnapshotIfNeeded is called
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let snapshotMade = try await manager.createSnapshotIfNeeded()
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// Then: No snapshot should be created
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XCTAssertFalse(snapshotMade)
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}
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func testCreateSnapshotIfNeeded_CreatesSnapshotWhenIntervalHasPassed() async throws {
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// Given: A snapshot was created more than 1 hour ago
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let oldDate = Date().addingTimeInterval(-60 * 61) // 61 minutes ago
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UserDefaults.standard.set(oldDate, forKey: "lastDatabaseSnapshotDate")
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// When: createSnapshotIfNeeded is called
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let snapshotMade = try await manager.createSnapshotIfNeeded()
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// Then: A snapshot should be created
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XCTAssertTrue(snapshotMade)
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// And: The last snapshot date should be updated
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let lastDate = UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate") as? Date
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XCTAssertNotNil(lastDate)
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XCTAssertTrue(lastDate! > oldDate)
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}
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// MARK: - Perform Snapshot Tests
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func testPerformSnapshot_WritesFile() async throws {
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// Given: No previous snapshot exists
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XCTAssertNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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let fileManager = FileManager.default
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guard let snapshotPath = Ndb.snapshot_db_path else {
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XCTFail("Snapshot path should be available")
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return
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}
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try fileManager.removeItem(atPath: snapshotPath)
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XCTAssertFalse(fileManager.fileExists(atPath: snapshotPath), "Snapshot directory should not exist at \(snapshotPath)")
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// When: Creating a snapshot
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let snapshotMade = try await manager.createSnapshotIfNeeded()
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// Then: Snapshot should be created
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XCTAssertTrue(snapshotMade)
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// And: The snapshot should be there
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var isDirectory: ObjCBool = false
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let exists = fileManager.fileExists(atPath: snapshotPath, isDirectory: &isDirectory)
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XCTAssertTrue(exists, "Snapshot directory should exist at \(snapshotPath)")
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XCTAssertTrue(isDirectory.boolValue, "Snapshot path should be a directory")
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// And: LMDB database files should exist
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let dataFile = "\(snapshotPath)/data.mdb"
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XCTAssertTrue(fileManager.fileExists(atPath: dataFile), "data.mdb should exist")
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}
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func testPerformSnapshot_UpdatesTimestamp() async throws {
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// Given: No previous snapshot
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XCTAssertNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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let beforeDate = Date()
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// When: Performing a snapshot
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try await manager.performSnapshot()
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let afterDate = Date()
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// Then: The timestamp should be set and within the time window
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let savedDate = UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate") as? Date
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XCTAssertNotNil(savedDate)
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XCTAssertGreaterThanOrEqual(savedDate!, beforeDate)
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XCTAssertLessThanOrEqual(savedDate!, afterDate)
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}
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func testPerformSnapshot_CanBeCalledMultipleTimes() async throws {
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// Given: A snapshot already exists
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try await manager.performSnapshot()
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// When: Performing another snapshot (this should replace the old one)
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try await manager.performSnapshot()
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// Then: No error should occur
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XCTAssertNotNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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}
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// MARK: - Periodic Snapshot Timer Tests
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func testStartPeriodicSnapshots_StartsTimer() async throws {
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// Given: Manager is initialized
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// When: startPeriodicSnapshots is called
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await manager.startPeriodicSnapshots()
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// Give the timer task a moment to execute
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try await Task.sleep(for: .milliseconds(100))
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// Then: A snapshot should be attempted
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let tickCount = await manager.snapshotTimerTickCount
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XCTAssertGreaterThan(tickCount, 0)
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}
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func testStartPeriodicSnapshots_DoesNotStartMultipleTimes() async throws {
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// Given: Timer is already started
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await manager.startPeriodicSnapshots()
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// Give the timer a moment to start
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try await Task.sleep(for: .milliseconds(500))
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let firstTickCount = await manager.snapshotTimerTickCount
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// When: startPeriodicSnapshots is called again
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await manager.startPeriodicSnapshots()
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// Give it a moment
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try await Task.sleep(for: .milliseconds(500))
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let secondTickCount = await manager.snapshotTimerTickCount
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// Then: The tick count should not have increased significantly
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// (proving we didn't start a second timer)
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XCTAssertEqual(secondTickCount, firstTickCount, "Starting twice should not create multiple timers")
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}
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func testStopPeriodicSnapshots_StopsTimer() async throws {
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// Given: Timer is running
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await manager.startPeriodicSnapshots()
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// When: stopPeriodicSnapshots is called and stats are reset
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await manager.stopPeriodicSnapshots()
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await manager.resetStats()
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// Wait longer than the timer interval
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try await Task.sleep(for: .milliseconds(200))
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// Then: No more snapshots should be created
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let snapshotCount = await manager.snapshotCount
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XCTAssertEqual(snapshotCount, 0)
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}
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func testStopPeriodicSnapshots_CanBeCalledMultipleTimes() async throws {
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// Given: Timer is running
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await manager.startPeriodicSnapshots()
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// When: stopPeriodicSnapshots is called multiple times
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await manager.stopPeriodicSnapshots()
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await manager.stopPeriodicSnapshots()
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// Then: No crash should occur (test passes if we get here)
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XCTAssertTrue(true)
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}
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// MARK: - Integration Tests
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func testSnapshotLifecycle_StartStopRestart() async throws {
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// Given: A manager with valid configuration
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// When: Starting, stopping, and restarting the timer
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await manager.startPeriodicSnapshots()
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try await Task.sleep(for: .milliseconds(100))
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await manager.stopPeriodicSnapshots()
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await manager.startPeriodicSnapshots()
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try await Task.sleep(for: .milliseconds(1000))
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// Then: Snapshots should be created appropriately
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let snapshotCount = await manager.snapshotCount
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XCTAssertGreaterThan(snapshotCount, 0)
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}
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func testSnapshotTimestampUpdates() async throws {
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// Given: No previous snapshot
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XCTAssertNil(UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate"))
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// When: Creating first snapshot
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try await manager.performSnapshot()
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let firstDate = UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate") as? Date
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XCTAssertNotNil(firstDate)
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// Wait to ensure time difference
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try await Task.sleep(for: .milliseconds(500))
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// Force another snapshot by clearing the date
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UserDefaults.standard.removeObject(forKey: "lastDatabaseSnapshotDate")
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try await manager.performSnapshot()
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let secondDate = UserDefaults.standard.object(forKey: "lastDatabaseSnapshotDate") as? Date
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XCTAssertNotNil(secondDate)
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// Then: Second date should be after first date
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XCTAssertGreaterThan(secondDate!, firstDate!, "Second snapshot timestamp should be later than first")
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}
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// MARK: - Error Handling Tests
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func testCreateSnapshotIfNeeded_HandlesErrors() async throws {
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// This test verifies that errors from performSnapshot are propagated
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// We can't easily test the actual error cases without mocking,
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// but we verify the method signature allows throwing
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// Given: A recent snapshot exists
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UserDefaults.standard.set(Date(), forKey: "lastDatabaseSnapshotDate")
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// When: Attempting to create a snapshot (should skip)
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let result = try await manager.createSnapshotIfNeeded()
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// Then: Should return false without throwing
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XCTAssertFalse(result)
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}
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// MARK: - Edge Case Tests
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func testSnapshotInterval_BoundaryCondition() async throws {
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// Given: A snapshot was created exactly 1 hour ago (the minimum interval)
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let exactlyOneHourAgo = Date().addingTimeInterval(-60 * 60)
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UserDefaults.standard.set(exactlyOneHourAgo, forKey: "lastDatabaseSnapshotDate")
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// When: Attempting to create a snapshot at the exact boundary
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let shouldCreate = try await manager.createSnapshotIfNeeded()
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// Then: A snapshot should be created (>= rather than > comparison)
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XCTAssertTrue(shouldCreate, "Snapshot should be created when exactly at minimum interval")
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}
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func testSnapshotInterval_JustBeforeBoundary() async throws {
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// Given: A snapshot was created 59 minutes and 59 seconds ago (just before the interval)
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let justBeforeOneHour = Date().addingTimeInterval(-60 * 59 - 59)
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UserDefaults.standard.set(justBeforeOneHour, forKey: "lastDatabaseSnapshotDate")
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// When: Attempting to create a snapshot
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let shouldCreate = try await manager.createSnapshotIfNeeded()
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// Then: No snapshot should be created
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XCTAssertFalse(shouldCreate, "Snapshot should not be created before minimum interval")
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}
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}
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// MARK: - SnapshotError Equatable Conformance for Testing
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extension SnapshotError: Equatable {
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public static func == (lhs: SnapshotError, rhs: SnapshotError) -> Bool {
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switch (lhs, rhs) {
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case (.pathsUnavailable, .pathsUnavailable):
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return true
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case (.copyFailed, .copyFailed):
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return true
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case (.removeFailed, .removeFailed):
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return true
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case (.directoryCreationFailed, .directoryCreationFailed):
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return true
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default:
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return false
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}
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}
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}
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