OCmock and MKReverseGeocoder - ocmock

Question

I would like to test a method that uses reverse Geocoding. What i would like to do is :
set the geocoder as a property of my controller
create the geocoder in the init method
call the geocoder in the method i want to test
replace the geocoder with a mock in my test
The problem is that the MKReverseGeocoder coordinate property is read only, i can only set it in the constructor method :
[[MKReverseGeocoder alloc] initWithCoordinate:coord]
And of course the coordinates are only available in the method i want to test..
Does anyone knows how i could mock the MKReverseGeocoder class ?
Thanks in advance,
Vincent.

Answer 1

Check out Matt Gallagher's great article on unit testing Cocoa applications. He provides a category extension to NSObject that allows you to replace instances at test time. I've used it to do something similar. I think your test would look something like this:
#import "NSObject+SupersequentImplementation.h"
id mockGeocoder = nil;
#implementation MKReverseGeocoder (UnitTests)
- (id)initWithCoordinate:(CLLocationCoordinate2D)coordinate {
if (mockGeocoder) {
// make sure the mock returns the coordinate passed in
[[[mockGeocoder stub] andReturn:coordinate] coordinate];
return mockGeocoder;
}
return invokeSupersequent(coordinate);
}
#end
...
-(void) testSomething {
mockGeocoder = [OCMockObject mockForClass:[MKReverseGeocoder class]];
[[mockGeocoder expect] start];
// code under test
[myObject geocodeSomething];
[mockGeocoder verify];
// clean up
mockGeocoder = nil;
}