Question

I’ve created a project with a Core Data model in it. The application looks for the model file (.momd) and runs just fine.

Unfortunately, the unit test keeps returning null:

NSURL *dataModelURL = [[NSBundle mainBundle] URLForResource:@"myDataModel" withExtension:@"momd"];

I can see the myDataModel.xdatamodeld folder and file in BOTH the main target and the unit testing target’s Compile Sources directory – but that doesn’t seem to be enough. What else am I missing in the unit test target?

Thanks,
-Luther

Answer 1

Unfortunately, a unit test target does not use the application’s main bundle but it creates a special UnitTest-bundle. So if you need to use bundled resources (like a Core Data model) within your tests, you need to work around that issue.

The most simple and most flexible workaround would be using the bundleForClass: method of NSBundle within your testing code. The parameter for that method can simply be given by [self class] within your tests. That way you can reuse this code without having to adjust the bundle identifiers in multiple projects.

Example:

- (void)testBundleLocation
{
    NSBundle *bundle = [NSBundle bundleForClass:[self class]];
    NSURL *url = [bundle URLForResource:@"myDataModel" withExtension:@"momd"];
    ...
}