Unit Testing - Core Data - page 178

1. Right-click the Services group under the CampgroundManagerTests group
and click New File .
2. Select Test Case Class . Click Next .
3. Name the class CamperServiceTests (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 .
In CamperServiceTests.swift , import the app and Core Data frameworks into the
test case, along with the other existing import statements:
import CampgroundManager
import CoreData
Add two properties to the class:
var camperService: CamperService !
var coreDataStack: CoreDataStack !
These properties will hold references to the CamperService instance to test and to
the Core Data stack. The properties are implicitly unwrapped optionals, since they'll
be initialized in setUp rather than in init .
Next, replace the implementation of setUp with the following:
override func setUp() {
super . setUp ()
coreDataStack = TestCoreDataStack()
camperService = CamperService (
managedObjectContext: coreDataStack . mainContext !,
coreDataStack: coreDataStack )
}
setUp is called before each test runs, and this is your chance to create any
resources required by all unit tests in the class. In this case, you initialize the
camperService and coreDataStack properties.
It's wise to reset your data after every test so that results are repeatable. Using the
in-memory store and creating a new context in setUp accomplishes this reset for
you.
Notice the CoreDataStack instance is actually a TestCoreDataStack instance. The
CamperService initialization method takes the context it needs and also an instance
of the CoreDataStack , since the context save methods are part of that class. You
can also use setUp() to insert standard test data into the context for use later.
Next, replace tearDown with the following implementation: