How to tear down Core Data Stack?

Question

I want to add unit tests for my Core Data app, but I am sure how to reset the context between tests.

This is my CoreDataStack object:

public final class CoreDataStack {
    var storeType: StoreType!
    public init(storeType: StoreType) {
        self.storeType = storeType
    }

    lazy var persistentContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: "Transaction")
        container.loadPersistentStores(completionHandler: { (description, error) in
            if let error = error {
                fatalError("Unresolved error \(error), \(error.localizedDescription)")
            } else {
                description.type = self.storeType.type

            }
        })

        return container
    }()

    public var context: NSManagedObjectContext {
        return persistentContainer.viewContext
    }
}

And this is how I am using it in my tests:

class PaymentTests: XCTestCase {

    var context: NSManagedObjectContext!

    override func setUp() {
        super.setUp()

        let coreDataStack = CoreDataStack(storeType: .inMemory)
        context = coreDataStack.context
    }
}

I tried to call context.reset() inside tearDown function but, the data is not reset, it's always persistent.

So how can I tear down the Core Data Stack ?

Answer 1

The old data has nothing to do with your context but with your PersistentStore. This is what you are using Core Data for, persist your data.

Delete the store to get rid of your data before initializing your stack in setup(). You can find it like this:

let storeUrl = persistentContainer.persistentStoreCoordinator.persistentStores.first!.url!

and remove it like this:

let fileManager = FileManager.default
fileManager.removeItem(at: storeUrl)