Unit Testing CoreData Example Code

MyCoreDataTests.h

#import <SenTestingKit/SenTestingKit.h>
#import <CoreData/CoreData.h>

@interface MyCoreDataTests : SenTestCase
{
    NSManagedObjectModel *managedObjectModel;
    NSPersistentStoreCoordinator *persistentStoreCoordinator;
    NSManagedObjectContext *managedObjectContext;
}
- (void)setupCoreDataEnvironment;
- (NSArray *)allEntities;
@end

MyCoreDataTests.m

#import "MyCoreDataTests.h"

@implementation MyCoreDataTests

- (void)setupCoreDataEnvironment
{
    // Destroy objects
    persistentStoreCoordinator = nil;
    managedObjectModel = nil;
    managedObjectContext = nil;
    
    // Setup Core Data
    managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] 
                                  initWithManagedObjectModel:managedObjectModel];
        
    NSError *error;
    
    // Setup an in memory store
    if(![persistentStoreCoordinator addPersistentStoreWithType:NSInMemoryStoreType 
                                                 configuration:nil 
                                                           URL:nil 
                                                       options:nil 
                                                         error:&error]) {
        STFail(@"Could not create store coordinator: %@", [error localizedDescription]);
    }
    
    managedObjectContext = [[NSManagedObjectContext alloc] init];
    [managedObjectContext setPersistentStoreCoordinator:persistentStoreCoordinator];
    [managedObjectContext setUndoManager:nil];

}

- (NSArray *)allEntities
{
    NSEntityDescription *entityDescription = [NSEntityDescription
                                              entityForName:@"Contact" inManagedObjectContext:managedObjectContext];
    
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    [request setEntity:entityDescription];
    
    NSArray *results = [managedObjectContext executeFetchRequest:request error:nil];
    
    return results;
}

- (void)testCanCreateEntity
{
    // Setup the CoreData environment
    [self setupCoreDataEnvironment];
    
    // Create an entity. Assume we have defined an Entity called Contact
    NSEntityDescription *createdContact = [NSEntityDescription insertNewObjectForEntityForName:@"Contact" 
                                                                        inManagedObjectContext: managedObjectContext];
    
    
    // We now should have a fresly created entity
    STAssertNotNil(createdContact, @"should have created a new entity");    
}


- (void)testAddedObject
{
    // Setup the CoreData environment
    [self setupCoreDataEnvironment];
    
    // We start of with an empty store
    int numberOfEntitiesBeforeCreatingOne = [[self allEntities] count];
    
    STAssertEquals(numberOfEntitiesBeforeCreatingOne, 0, @"no entities should be present");
    
    // Create an entity
    [NSEntityDescription insertNewObjectForEntityForName:@"Contact" 
                                  inManagedObjectContext: managedObjectContext];
    
    
    // The new entity has been added to the store
    int numberOfEntitiesAfterCreatingOne = [[self allEntities] count];
    
    STAssertEquals(numberOfEntitiesAfterCreatingOne, 1, @"one entity should be present");
}
@end

MyCoreDataTests_SetupCoreDataEnvironment.m

- (void)setupCoreDataEnvironment
{
    // Destroy objects
    persistentStoreCoordinator = nil;
    managedObjectModel = nil;
    managedObjectContext = nil;
    
    // Setup Core Data
    managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
    
    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] 
                                  initWithManagedObjectModel:managedObjectModel];
        
    NSError *error;
    
    // Setup an in memory store
    if(![persistentStoreCoordinator addPersistentStoreWithType:NSInMemoryStoreType 
                                                 configuration:nil 
                                                           URL:nil 
                                                       options:nil 
                                                         error:&error]) {
        STFail(@"Could not create store coordinator: %@", [error localizedDescription]);
    }
    
    managedObjectContext = [[NSManagedObjectContext alloc] init];
    [managedObjectContext setPersistentStoreCoordinator:persistentStoreCoordinator];
    [managedObjectContext setUndoManager:nil];

}

MyCoreDataTests_testAddedObject.m

- (NSArray *)allEntities
{
    NSEntityDescription *entityDescription = [NSEntityDescription
                                              entityForName:@"Contact" inManagedObjectContext:managedObjectContext];
    
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    [request setEntity:entityDescription];
    
    NSArray *results = [managedObjectContext executeFetchRequest:request error:nil];
    
    return results;
}

- (void)testAddedObject
{
    // Setup the CoreData environment
    [self setupCoreDataEnvironment];
    
    // We start of with an empty store
    int numberOfEntitiesBeforeCreatingOne = [[self allEntities] count];
    
    STAssertEquals(numberOfEntitiesBeforeCreatingOne, 0, @"no entities should be present");
    
    // Create an entity
    [NSEntityDescription insertNewObjectForEntityForName:@"Contact" 
                                  inManagedObjectContext: managedObjectContext];
    
    
    // The new entity has been added to the store
    int numberOfEntitiesAfterCreatingOne = [[self allEntities] count];
    
    STAssertEquals(numberOfEntitiesAfterCreatingOne, 1, @"one entity should be present");
}

MyCoreDataTests_testCanCreateEnity.m

- (void)testCanCreateEntity
{
    // Setup the CoreData environment
    [self setupCoreDataEnvironment];
    
    // Create an entity. Assume we have defined an Entity called Contact
    NSEntityDescription *createdContact = [NSEntityDescription insertNewObjectForEntityForName:@"Contact" 
                                                                        inManagedObjectContext: managedObjectContext];
    
    
    // We now should have a fresly created entity
    STAssertNotNil(createdContact, @"should have created a new entity");    
}

MyCoreDataTestsStep1.h

#import <SenTestingKit/SenTestingKit.h>
#import <CoreData/CoreData.h>

@interface MyCoreDataTests : SenTestCase
{
    NSManagedObjectModel *managedObjectModel;
    NSPersistentStoreCoordinator *persistentStoreCoordinator;
    NSManagedObjectContext *managedObjectContext;
}
@end

MyCoreDataTestsStep2.h

#import <SenTestingKit/SenTestingKit.h>
#import <CoreData/CoreData.h>

@interface MyCoreDataTests : SenTestCase
{
    NSManagedObjectModel *managedObjectModel;
    NSPersistentStoreCoordinator *persistentStoreCoordinator;
    NSManagedObjectContext *managedObjectContext;
}
- (void)setupCoreDataEnvironment;
@end