Unit Testing - Core Data - page 182

Here's a breakdown of the code:
1. You create a text expectation linked to a notification. In this case, the
expectation is linked to NSManagedObjectContextDidSaveNotification from the root
context of the Core Data stack. The handler for the notification is simple—it
returns true since all you care about is that the notification is fired.
2. You add the camper, exactly the same as before.
3. The test waits up to two seconds for the expectation. If there are errors or the
timeout passes, the error parameter for the handler block will contain a value.
It's important to keep UI-blocking operations such as Core Data saving off the main
thread so your app stays responsive. Test expectations are invaluable to make sure
these asynchronous operations are covered by unit tests.
You've added tests for existing features in the app; now it's time to add some
features yourself. [TODO: Sentence fragment?] Along with the tests too, of course.
Or for even more fun: perhaps write the tests first?
Tests first
An important function of CampgroundManager its ability to reserve sites for
campers. Before it can accept reservations, the system has to know about all of the
campsites at the campground. I created CampSiteService to help with adding,
deleting and finding campsites.
Open CampSiteService , and you'll notice the only method I've implemented is
addCampSite . There are no unit tests for this method, so start by creating a test
case for the service:
1. Right-click Services under the CampgroundManagerTests group and click
New File .
2. Select Test Case Class . Click Next .
3. Name the class CampSiteServiceTests (subclass of XCTestCase should
already be selected) and pick Swift for the language.
4. Make sure the CampgroundManagerTests target checkbox is the only target
selected. Click Create .
Replace the contents of the file with the following:
import UIKit
import XCTest
import CampgroundManager
import CoreData
class CampSiteServiceTests: XCTestCase {
var campSiteService: CampSiteService !
var coreDataStack: CoreDataStack !