Can I build a Unit Test for an External Service (iPhone)?

Question

My app registers with an external service. The service phones me up with a two-digit code that I have to enter in (first time only) in order to use the service. The rest of the calls to the service work fine afterwards.

How would I set up a unit test for a method that isn't complete until a response code is entered out of band?

Any ideas? iOS SDK 4.2

Answer 1

Use OCMock to mock the service, that allows you to use stubbing and return the expected result.

For example:

Let's say this is your service:

@interface ServiceClass
- (NSString *) fetchData;
@end

This would be your mock service

id serviceMock = [[OCMockObject niceMockForClass:[ServiceClass class]];
[[[serviceMock stub] andreturn:@"56"] fetchData];
// we tell the mock to return the string "56" when the method fetchData is called

SomeViewController *mvc = [[SomeViewController alloc] init];
mvc.webService = serviceMock;
// Here we are injecting a mock into a view controller

You can use some Dependency injection techniques to inject this mock into your view controller

@synthesize webService = _webService;

- (IBAction)buttonClicked:(id)sender
{
   NSString *result = [self.webService fetchData];
}

- (ServiceClass *)webService
{
   if (!_webService)
   {
      _webService = [[ServiceClass alloc] init];
   }

   return _webService;
}