URL template tags fail in Test mode, but work in Dev and Production ( Django 1.2.1 )

Question

I've been trying to add the django-lean app to my project.

I have not been able to get the tests to pass. It took me a few days with a debugger to determine what the problem was.

It seems that all the URL template tags fail in Test mode, but not in Production nor Developement.

Failure happens in django.template.defaulttags.URLNode.render() line 366:

url = reverse(self.view_name, args=args, kwargs=kwargs, current_app=context.current_app)

The error message is:

NoReverseMatch: Reverse for 'index' with arguments '()' and keyword arguments '{}' not found.

If I replace the URL template tag with a relative link, the test just fails the next time a URL node is encountered.

I have confirmed that:

reverse('index') 

call works in the shell.

What could be going wrong?