Unit testing with core data in objective c - objective-c

Question

My coredata methods are here. How to write unit test case to check this.
Method to save to coredata
- (void)saveUserDetails:(Model *)userDetail {
if(userDetail != nil) {
UserEntity *user = [NSEntityDescription insertNewObjectForEntityForName:#“EntityName” inManagedObjectContext:[self sharedContext]];
NSArray *fetchArray = [self fetchUserWithUsername:userDetail.username];
if ([fetchArray count] == 0) {
user.username = userDetail.username;
[self saveContext];
}
}
}
Method to fetch from coredata
- (NSArray *)fetchUserWithUsername:(NSString *)username {
if (username != nil) {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *userEntity = [NSEntityDescription entityForName:#“EntityName” inManagedObjectContext:[self sharedContext]];
[fetchRequest setEntity:userEntity];
fetchRequest.predicate = [NSPredicate predicateWithFormat:#"username = %#", username];
NSError *error;
NSArray *fetchedObjects = [[self sharedContext] executeFetchRequest:fetchRequest error:&error];
return fetchedObjects;
}
return nil;
}

Answer 1

Create an in-memory store and inject this into your object.
NSURL *modelURL = [[NSBundle mainBundle] URLForResource:#"MyResource" withExtension:#"momd"];
NSManagedObjectModel *mom = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
NSPersistentStoreCoordinator *psc = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:mom];
XCTAssertTrue([psc addPersistentStoreWithType:NSInMemoryStoreType configuration:nil URL:nil options:nil error:NULL] ? YES : NO, #"Should be able to add in-memory store");
NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
context.persistentStoreCoordinator = psc;