iPhone Unit Testing Toolkit

Posted on by in Development, Process

As we get in to developing iPhone/Touch applications at Carbon Five, we obviously want to bring over all our best agile practices including test driven development (TDD).

I’ve been bootstrapping with the beta version of the Pragmatic iPhone SDK Development book but was disappointed to find no discussion of unit testing for the iPhone. So I’ve been piecing it together as I go.


Unit testing in Objective-C is provided by the SenTestingKit framework that installs with XCode in /Developer/Library/Frameworks/. However it is not compatible with the iPhone SDK. The Google Toolbox for Mac provides an implementation of SenTestCase for the iPhone that I am using instead. The instructions provided on that page worked for me with one exception that I included as a comment on that page:

I followed the instructions above but was unable to see any messages in the console. I did not see the behavior described above as:

Your target should now build cleanly, and if you check the build log you should see something like: “Executed 0 tests, with 0 failures (0 unexpected) in 0.001 (0.001) seconds” at the end.

It turned out that I needed to set the base SDK in the inspector for my target to an iPhone simulator even though the Overview showed I was building for simulator debugging.

I created a ‘Unit Tests’ target per the GTM directions to run my tests. Now I am happily running my tests with command-B. One point that could be a problem when getting into continuous integration is that my Unit Tests target reports ‘Build succeeded (1 error)’ when a unit test fails instead of having the build actually fail.

I have not gotten into the “Advanced Stuff” described on that page.


The SenTestingKit assertion methods are pretty lame. They’re verbose and require that you provide a string message for your expectation (e.g. STAssertEqualStrings(a1, a2, description, …)). We’re using and like Hamcrest on many of our Java projects. I was psyched to see there is an Objective-C implementation OCHamcrest.

There is no download available for Hamcrest Objective-C so I checked it out from SVN and built the framework product in Xcode for OS X 10.5/i386.

I struggled for a while to get the dependency on the hamcrest.framework build product into my project. I ended up with this solution:

  1. Create a ‘Frameworks’ folder in my project root
  2. Copy hamcrest.framework to Frameworks/
  3. In Xcode, right click on ‘Frameworks’ and ‘Add existing framework…”
  4. Browse to the hamcrest.framework folder and add it, making sure to add it to my Unit Tests target only
  5. Right click on the Unit Tests target to add a new Copy Files Build Phase that copies to the Products directory and put that build phase early in the target steps
  6. Add hamcrest.framework to that build phase by dragging from Frameworks
  7. Include Hamcrest in your test class and you’re good to go
#import "GTMSenTestCase.h"

@interface ExampleWithAssertThat : SenTestCase

@implementation ExampleWithAssertThat

- (void) testUsingAssertThat
    assertThat(@"xx", is(@"xx"));
    assertThat(@"yy", isNot(@"xx"));
    assertThat(@"i like cheese", containsString(@"cheese"));



iPhone development requires a lot of mucking around with UI framework classes like UITableView, UIApplicationDelegate and so on. These classes have a lot of dependencies and are depended upon all over the place which can make it hard to get them under test.

Mock objects are a great solution to this problem and OCMock provides an implementation for Objective-C. In this case, the OCMock.framework provided in the OCMock binary release worked for me when installed in the same manner as described for Hamcrest above.

This example of testing [UIApplicationDelegate applicationDidFinishLaunching] illustrates its use pretty well. I have a simple test that creates a mock UITableView to asserts a cell is correctly created in [UITableViewController tableView:cellForRowAtIndexPath:]. It looks like:

#import "GTMSenTestCase.h"

#import "SortedStateViewController.h"
#import "Country.h"

@interface SortedStateViewControllerTest : SenTestCase {}

SortedStateViewController *controller;


@implementation SortedStateViewControllerTest

- (void) setUp {
    controller = [[SortedStateViewController alloc] init];
    Country *country = [[Country alloc] init];
    [country addState:@"New York" withPopulation:19306183 andArea:47213];
    [country addState:@"California" withPopulation:36457549     andArea:155959];
    controller.country = country;
    controller.key = @"population";

- (void) testPopulatesCell {
    id tableView = [OCMockObject mockForClass:[UITableView class]];
    [[tableView stub] dequeueReusableCellWithIdentifier:[OCMConstraint any]];
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:(NSUInteger)0

    UITableViewCell *cell = [controller tableView:tableView
    assertThat(@"California", equalTo(cell.text));


Continuous Integration

So I’m pretty happy with where this is now. I’m working through the Pragmatic book TDD as I go. It’s also have an ObjectiveCTest that I add assertions to as I play with features of the language.

Missing from this toolkit is a good continuous integration solution.

There is now a recently released Xcode builder for CruiseControl. However, we use Bamboo for CI for our Java and Ruby projects and are considering moving to TeamCity. It looks like there is an Xcode plugin for TeamCity and some attempts with Bamboo.

More on that later.