具有内存存储的核心数据堆栈的单元测试不断失败

Question

具有内存存储的核心数据堆栈的单元测试不断失败

我正在建立一个个人项目，让我和我的妻子监控我们的杂货消费习惯。该应用程序使用了 Core Data，我在进行单元测试时遇到了困难。我正在测试我的CoreDataStack类以确保它的方法正在保存和删除对象。

这是CoreDataStack：

internal class CoreDataStack {

    // MARK: - Properties

    private let modelName: String

    internal lazy var storeContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: self.modelName)
        container.loadPersistentStores { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        }
        return container
    }()

    internal lazy var managedContext: NSManagedObjectContext = {
        return self.storeContainer.viewContext
    }()

    // MARK: - Initialization

    internal init(modelName: String = "Cart") {
        self.modelName = modelName
    }

    // MARK: - Saving

    internal func saveContext() {
        guard managedContext.hasChanges else {
            return
        }
        do {
            try managedContext.save()
        } catch let error as NSError {
            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    }

    // MARK: - Deleting

    internal func delete(object: NSManagedObject, from context: NSManagedObjectContext) {
        context.delete(object)
    }

    internal func delete(allObjectsForEntity entity: String, from context: NSManagedObjectContext) {
        let deleteFetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
        let batchDeleteRequest = NSBatchDeleteRequest(fetchRequest: deleteFetchRequest)
        do {
            try storeContainer.persistentStoreCoordinator.execute(batchDeleteRequest, with: context)
        } catch let error as NSError {
            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    }

}

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我在我的测试目标中创建了一个CoreDataStack名为的子类TestCoreDataStack。TestCoreDataStack使用内存存储，以便在包含测试完成时将其销毁。

这是TestCoreDataStack：

internal final class TestCoreDataStack: CoreDataStack {

    // MARK: - Initialization

    internal override init(modelName: String = "Cart") {
        super.init(modelName: modelName)
        let persistentStoreDescription = NSPersistentStoreDescription()
        persistentStoreDescription.type = NSInMemoryStoreType
        let container = NSPersistentContainer(name: modelName)
        container.persistentStoreDescriptions = [persistentStoreDescription]
        container.loadPersistentStores { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        }
        self.storeContainer = container
    } 
}

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我还有一个助手类，ManagedObjectFetcher，它只包含在我的测试目标中，仅用于在保存或删除托管对象后获取它们。使用此类以便我可以验证计数以及在保存或删除对象后是否存在正确的信息。

她的是ManagedObjectFetcher：

internal final class ManagedObjectFetcher {

    // MARK: - Properties

    private let coreDataStack: CoreDataStack

    // MARK: - Initialization

    internal init(coreDataStack: CoreDataStack) {
        self.coreDataStack = coreDataStack
    }

    // MARK: - All Records

    internal func allRecords<T: NSManagedObject>(for entity : T.Type) -> [T] {
        let request = T.fetchRequest()
        do {
            guard let results = try coreDataStack.managedContext.fetch(request) as? [T] else {
                fatalError("Invalid results")
            }
            return results
        } catch {
            fatalError("Error with request: \(error)")
        }
    }

}

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CoreDataStackTests是我XCTestCase用于测试CoreDataStack以确保对象被保存或删除的子类。

这是CoreDataStackTests：

internal final class CoreDataStackTests: XCTestCase {

    // MARK: - Properties

    private var coreDataStack: TestCoreDataStack!

    private var managedObjectFetcher: ManagedObjectFetcher!

    // MARK: - Test Lifecycle

    override func setUp() {
        super.setUp()
        coreDataStack = TestCoreDataStack()
        managedObjectFetcher = ManagedObjectFetcher(coreDataStack: coreDataStack)
    }

    override func tearDown() {
        coreDataStack = nil
        managedObjectFetcher = nil
        super.tearDown()
    }

    // MARK: - Saving

    // Test 1
    internal func test_CoreDataStack_Saves_GroceryItem() {
        let preResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(preResults.count, 0, "Expected `0`")
        let _ = GroceryItem(name: "Name", singleItemPrice: Decimal(0.99), quantity: 1, date: Date(), isTaxable: true, managedObjectContext: coreDataStack.managedContext)
        coreDataStack.saveContext()
        let postResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(postResults.count, 1, "Expected `1`")
    }

    // MARK: - Deleting

    // Test 2
    internal func test_CoreDataStack_Deletes_GroceryItem() {
        let initialResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(initialResults.count, 0, "Expected `0`")
        let item = GroceryItem(name: "Name", singleItemPrice: Decimal(0.99), quantity: 1, date: Date(), isTaxable: true, managedObjectContext: coreDataStack.managedContext)
        coreDataStack.saveContext()
        let preResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(preResults.count, 1, "Expected `1`")
        coreDataStack.delete(object: item, from: coreDataStack.managedContext)
        coreDataStack.saveContext()
        let postResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(postResults.count, 0, "Expected `0`")
    }

    // Test 3
    internal func test_CoreDataStack_Deletes_AllGroceryItems() {
        let initialResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(initialResults.count, 0, "Expected `0`")
        let _ = GroceryItem(name: "Name", singleItemPrice: Decimal(0.99), quantity: 1, date: Date(), isTaxable: true, managedObjectContext: coreDataStack.managedContext)
        let _ = GroceryItem(name: "Another Name", singleItemPrice: Decimal(5.99), quantity: 2, date: Date(), isTaxable: false, managedObjectContext: coreDataStack.managedContext)
        coreDataStack.saveContext()
        let preResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(preResults.count, 2, "Expected `2`")
        coreDataStack.delete(allObjectsForEntity: GroceryItem.description(), from: coreDataStack.managedContext)
        coreDataStack.saveContext()
        let postResults = managedObjectFetcher.allRecords(for: GroceryItem.self)
        XCTAssertEqual(postResults.count, 0, "Expected `0`")
    }

}

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在中执行测试时CoreDataStackTests，我遇到了以下无法解决的问题：

测试 1：单独运行时测试通过。当所有测试CoreDataStack测试都运行时，它通过或失败。
测试 2：单独运行时测试通过。当所有测试CoreDataStack测试都运行时，它通过或失败。
测试 3：无论是单独运行还是与其他测试一起运行，该测试都不会通过。每次运行try storeContainer.persistentStoreCoordinator.execute(batchDeleteRequest, with: context)的delete(allObjectsForEntity entity: String, from context: NSManagedObjectContext)方法内部都会遇到一个测试失败断点CoreDataStack。

这是我在运行所有三个测试后得到的控制台输出：

Test Suite 'Selected tests' started at 2017-07-03 21:24:01.609
Test Suite 'CartTests.xctest' started at 2017-07-03 21:24:01.610
Test Suite 'CoreDataStackTests' started at 2017-07-03 21:24:01.610
Test Case '-[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_AllGroceryItems]' started.
<unknown>:0: error: -[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_AllGroceryItems] : failed: caught "NSInternalInconsistencyException", "Unknown command type <NSBatchDeleteRequest : resultType : 0, fetch :<NSFetchRequest: 0x6000000de450> (entity: GroceryItem; predicate: ((null)); sortDescriptors: ((null)); type: NSManagedObjectIDResultType; includesPropertyValues: NO; includesPendingChanges: NO; ) >"
(
    0   CoreFoundation                      0x000000010c90079b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010bd2e121 objc_exception_throw + 48
    2   CoreData                            0x000000010c34febf -[NSMappedObjectStore executeRequest:withContext:error:] + 303
    3   CoreData                            0x000000010c3f0f6d __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke + 2509
    4   CoreData                            0x000000010c3e9126 __55-[NSPersistentStoreCoordinator _routeHeavyweightBlock:]_block_invoke + 86
    5   CoreData                            0x000000010c3fcda9 gutsOfBlockToNSPersistentStoreCoordinatorPerform + 185
    6   libdispatch.dylib                   0x0000000110bfbbb9 _dispatch_client_callout + 8
    7   libdispatch.dylib                   0x0000000110c02500 _dispatch_queue_barrier_sync_invoke_and_complete + 92
    8   CoreData                            0x000000010c3e8ab5 _perform + 213
    9   CoreData                            0x000000010c3e8e3b -[NSPersistentStoreCoordinator _routeHeavyweightBlock:] + 283
    10  CoreData                            0x000000010c2f2aba -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 634
    11  Cart                                0x000000010b40b667 _T04Cart13CoreDataStackC16deleteAllObjectsySS9forEntity_So22NSManagedObjectContextC4fromtF + 391
    12  CartTests                           0x00000001240ea070 _T09CartTests013CoreDataStackB0C05test_cdE24_Deletes_AllGroceryItemsyyF + 3344
    13  CartTests                           0x00000001240eabc4 _T09CartTests013CoreDataStackB0C05test_cdE24_Deletes_AllGroceryItemsyyFTo + 36
    14  CoreFoundation                      0x000000010c884f8c __invoking___ + 140
    15  CoreFoundation                      0x000000010c884e60 -[NSInvocation invoke] + 320
    16  XCTest                              0x00000001224dd6e0 __24-[XCTestCase invokeTest]_block_invoke_2 + 451
    17  XCTest                              0x0000000122524bed -[XCUITestContext performInScope:] + 187
    18  XCTest                              0x00000001224dd4f8 -[XCTestCase invokeTest] + 254
    19  XCTest                              0x00000001224de424 __26-[XCTestCase performTest:]_block_invoke.362 + 42
    20  XCTest                              0x0000000122529432 +[XCTContext runInContextForTestCase:block:] + 163
    21  XCTest                              0x00000001224dddc0 -[XCTestCase performTest:] + 608
    22  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    23  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    24  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    25  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    26  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    27  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    28  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    29  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    30  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    31  XCTest                              0x0000000122530625 __44-[XCTTestRunSession runTestsAndReturnError:]_block_invoke + 40
    32  XCTest                              0x00000001224ecb99 -[XCTestObservationCenter _observeTestExecutionForBlock:] + 480
    33  XCTest                              0x00000001225304c4 -[XCTTestRunSession runTestsAndReturnError:] + 281
    34  XCTest                              0x00000001224c9d43 -[XCTestDriver runTestsAndReturnError:] + 254
    35  XCTest                              0x00000001225286b7 _XCTestMain + 616
    36  CoreFoundation                      0x000000010c8a3dcc __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    37  CoreFoundation                      0x000000010c88833b __CFRunLoopDoBlocks + 203
    38  CoreFoundation                      0x000000010c887b34 __CFRunLoopRun + 1060
    39  CoreFoundation                      0x000000010c887499 CFRunLoopRunSpecific + 409
    40  GraphicsServices                    0x00000001121d79d7 GSEventRunModal + 62
    41  UIKit                               0x000000010cd7f0b8 UIApplicationMain + 159
    42  Cart                                0x000000010b40e637 main + 55
    43  libdyld.dylib                       0x0000000110c71771 start + 1
    44  ???                                 0x0000000000000005 0x0 + 5
)
Test Case '-[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_AllGroceryItems]' failed (2636.006 seconds).
Test Case '-[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_GroceryItem]' started.
<unknown>:0: error: -[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_GroceryItem] : failed: caught "NSInvalidArgumentException", "executeFetchRequest:error: <null> is not a valid NSFetchRequest."
(
    0   CoreFoundation                      0x000000010c90079b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010bd2e121 objc_exception_throw + 48
    2   CoreData                            0x000000010c2f11d8 -[NSManagedObjectContext executeFetchRequest:error:] + 792
    3   CartTests                           0x00000001240eb1f7 _T09CartTests20ManagedObjectFetcherC10allRecordsSayxGxm3for_tSo09NSManagedD0CRbzlF + 247
    4   CartTests                           0x00000001240e7d86 _T09CartTests013CoreDataStackB0C05test_cdE20_Deletes_GroceryItemyyF + 182
    5   CartTests                           0x00000001240e9344 _T09CartTests013CoreDataStackB0C05test_cdE20_Deletes_GroceryItemyyFTo + 36
    6   CoreFoundation                      0x000000010c884f8c __invoking___ + 140
    7   CoreFoundation                      0x000000010c884e60 -[NSInvocation invoke] + 320
    8   XCTest                              0x00000001224dd6e0 __24-[XCTestCase invokeTest]_block_invoke_2 + 451
    9   XCTest                              0x0000000122524bed -[XCUITestContext performInScope:] + 187
    10  XCTest                              0x00000001224dd4f8 -[XCTestCase invokeTest] + 254
    11  XCTest                              0x00000001224de424 __26-[XCTestCase performTest:]_block_invoke.362 + 42
    12  XCTest                              0x0000000122529432 +[XCTContext runInContextForTestCase:block:] + 163
    13  XCTest                              0x00000001224dddc0 -[XCTestCase performTest:] + 608
    14  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    15  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    16  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    17  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    18  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    19  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    20  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    21  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    22  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    23  XCTest                              0x0000000122530625 __44-[XCTTestRunSession runTestsAndReturnError:]_block_invoke + 40
    24  XCTest                              0x00000001224ecb99 -[XCTestObservationCenter _observeTestExecutionForBlock:] + 480
    25  XCTest                              0x00000001225304c4 -[XCTTestRunSession runTestsAndReturnError:] + 281
    26  XCTest                              0x00000001224c9d43 -[XCTestDriver runTestsAndReturnError:] + 254
    27  XCTest                              0x00000001225286b7 _XCTestMain + 616
    28  CoreFoundation                      0x000000010c8a3dcc __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12
    29  CoreFoundation                      0x000000010c88833b __CFRunLoopDoBlocks + 203
    30  CoreFoundation                      0x000000010c887b34 __CFRunLoopRun + 1060
    31  CoreFoundation                      0x000000010c887499 CFRunLoopRunSpecific + 409
    32  GraphicsServices                    0x00000001121d79d7 GSEventRunModal + 62
    33  UIKit                               0x000000010cd7f0b8 UIApplicationMain + 159
    34  Cart                                0x000000010b40e637 main + 55
    35  libdyld.dylib                       0x0000000110c71771 start + 1
    36  ???                                 0x0000000000000005 0x0 + 5
)
Test Case '-[CartTests.CoreDataStackTests test_CoreDataStack_Deletes_GroceryItem]' failed (11.969 seconds).
Test Case '-[CartTests.CoreDataStackTests test_CoreDataStack_Saves_GroceryItem]' started.
<unknown>:0: error: -[CartTests.CoreDataStackTests test_CoreDataStack_Saves_GroceryItem] : failed: caught "NSInvalidArgumentException", "executeFetchRequest:error: <null> is not a valid NSFetchRequest."
(
    0   CoreFoundation                      0x000000010c90079b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010bd2e121 objc_exception_throw + 48
    2   CoreData                            0x000000010c2f11d8 -[NSManagedObjectContext executeFetchRequest:error:] + 792
    3   CartTests                           0x00000001240eb1f7 _T09CartTests20ManagedObjectFetcherC10allRecordsSayxGxm3for_tSo09NSManagedD0CRbzlF + 247
    4   CartTests                           0x00000001240e6fe6 _T09CartTests013CoreDataStackB0C05test_cdE18_Saves_GroceryItemyyF + 182
    5   CartTests                           0x00000001240e7cb4 _T09CartTests013CoreDataStackB0C05test_cdE18_Saves_GroceryItemyyFTo + 36
    6   CoreFoundation                      0x000000010c884f8c __invoking___ + 140
    7   CoreFoundation                      0x000000010c884e60 -[NSInvocation invoke] + 320
    8   XCTest                              0x00000001224dd6e0 __24-[XCTestCase invokeTest]_block_invoke_2 + 451
    9   XCTest                              0x0000000122524bed -[XCUITestContext performInScope:] + 187
    10  XCTest                              0x00000001224dd4f8 -[XCTestCase invokeTest] + 254
    11  XCTest                              0x00000001224de424 __26-[XCTestCase performTest:]_block_invoke.362 + 42
    12  XCTest                              0x0000000122529432 +[XCTContext runInContextForTestCase:block:] + 163
    13  XCTest                              0x00000001224dddc0 -[XCTestCase performTest:] + 608
    14  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    15  XCTest                              0x00000001224d9f8d -[XCTestSuite _performProtectedSectionForTest:testSection:] + 26
    16  XCTest                              0x00000001224da171 -[XCTestSuite performTest:] + 214
    17  XCTest                              0x00000001224da396 __27-[XCTestSuite performTest:]_block_invoke + 295
    18  XCTest

Answer 1

小智 6

不幸的是，CoreData 内存存储不支持批量删除：

重要提示：批量删除仅在您使用 SQLite 持久存储时可用。

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