Let me tell you, dear reader, how I simplify my life by writing small and effective unit tests for iOS projects.

I’m quite lazy person, so if I can simplify my life and work - I do so. Of course you agree, that writing tests is cool. Having tests means you have less bugs in code, and if someone changes something, he can check if he’s patch breaks anything in existing implementation. And of course, writing unit tests makes you thinking about better architecture, and making smaller, better methods. You know beforehand, that testing a method that is few hundreds of lines of code is a big pain in the ass…

But why people often avoid writing tests? Well, as I see often - because they think it’s a lot of additional code to write.

So I’ll try to tell from my experience, how to write less test code :)


Let’s start with simple thing, thing that you can spot in many test samples:

STAssertNotNil(objects, @"Could not load objects");

Well, if it’s one line in code - it’s kind of OK. But if you need to write these STAssers-s over 9000 times… you know what I mean. It’s getting even worse if you want to compare simple types like int or float.

So my number one pick is a small library called Expecta. Just add to your Podfile (I think you’r using cocoapods, don’t you?) pod 'Expecta' and you’ll have a simple and nice assert tests like


// or more fancy stuff
NSDictionary *dict2 = @{@"id" : @"articleId", @"name" : @"name", @"title" : @"title"};

HTTP requests

A lot of developers find it hard to test their API-classes and network-related code. Well, I’ll give you some tips on it.

I’m using Nocilla library. (pod 'Nocilla'). It’s a small library that can stub some network requests, and return back stuff like Headers, response code, etc. It’s in active development, so if you want to refer to latest code, you should put in your Podfile pod 'Nocilla', podspec: 'https://github.com/luisobo/Nocilla/raw/master/Nocilla.podspec'

Some code samples:

NSString *data = @"Some data here";
stubRequest(@"GET", @"http://localhost/articles").
andReturn(200).withHeaders(@{@"Content-Type": @"application/json"}).withBody(data);

Now if you’ll make a normal NSURLRequest to http://localhost/articles you’ll get a response code 200, Header Content-Type: application/json and, of course, your piece of data :). Oh, and don’t forget to initialize and clear the stubs:

- (void)setUp {
    [[LSNocilla sharedInstance] start];
- (void)tearDown {
    // Clear Network stubs
    [[LSNocilla sharedInstance] clearStubs];
    [[LSNocilla sharedInstance] stop];

Asynchronous testing

Network tests have delays. yep. and you need to deal with them. And your tests need to wait for it. Same for blocks. Methods, where you need to check return values in blocks need asynchronous testing.

In internet, you can find a lot of examples how to do that. The one I’ve used is

dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
[Thing doSomethingOnSuccess:^(NSArray *objects) {
    } failure:^(NSError *error) {
while (dispatch_semaphore_wait(semaphore, DISPATCH_TIME_NOW)) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                                 beforeDate:[NSDate dateWithTimeIntervalSinceNow:2]];

Writing this once - kind of OK. But again, we can make it simpler. Personally, I’ve created a small library for that. TKSenTestAsync. Just add pod 'TKSenTestAsync' and the code above can be re-written as

[self runTestWithBlock:^{
        [Thing doSomethingOnSuccess:^(NSArray *objects) {
         [self blockTestCompleted]; // required
    } failure:^(NSError *error) {
        [self blockTestCompleted]; // required

looks much more clear?

CoreData and.. yeah, RestKit stuff

Well, currently I’m using RestKit a lot, and a nice thing about it, that it has few nice helpers for Unit testing.

First of all, you need to add it’s testing sub-library. Currently, due to some bug in main cocoapods spec, you need to write in your Podfile:

pod 'RestKit', podspec: 'https://github.com/RestKit/RestKit/raw/development/RestKit.podspec'
pod 'RestKit/Testing', podspec: 'https://github.com/RestKit/RestKit/raw/development/RestKit.podspec'

Now, before starting, check that you have included Your.xcdatamodeld in Unit tests target.

Setting up stuff:

        RKManagedObjectStore *store = [RKTestFactory managedObjectStore];
        [RKManagedObjectStore setDefaultStore:store];

Now I found a small bug in this step… in my case, a directory was missing in iPhone Simulator, so the above code was failing. To fix this, just run following before

+ (void)checkPathForCoreDataFile {
    NSString *path = RKApplicationDataDirectory();
    NSError *error = nil;
    BOOL isDir = YES;
    NSFileManager *fm= [NSFileManager defaultManager];
    if (![fm fileExistsAtPath:path isDirectory:&isDir]) {
        if (![fm createDirectoryAtPath:path withIntermediateDirectories:YES attributes:nil error:&error]) {
            NSLog(@"Error: Create folder failed");

Now, let’s test it:

- (void)testCoreDataIntegration {
    RKManagedObjectStore *managedObjectStore = [RKManagedObjectStore defaultStore];


    NSManagedObjectContext *moc = managedObjectStore.persistentStoreManagedObjectContext;

    Article *mo = [RKTestFactory insertManagedObjectForEntityForName:@"Article" inManagedObjectContext:moc withProperties:nil];
    mo.title = @"SomeObject";

    [moc saveToPersistentStore:NULL];


    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Article"];

    NSError *error = nil;
    NSArray *objects = [moc executeFetchRequest:fetchRequest error:&error];


Putting it all together

I can write a lot of code here, but the easiest thing is to point you to the library I’m currently developing, which includes all this tests: RKInjective

You should check the RKInjectiveTests folder contents.

My next article will be about testing a small game engine using Kiwi test framework.

The end.

Well, I hope you liked the stuff I covered here. I hope it can help you in your work. Please leave your comments, tweets, etc. I’ll be happy.