Like execute, but records a skip if the should_skip method returns True.

def run(self, context=None, stdout=None, stderr=None):
        "Like execute, but records a skip if the should_skip method returns True."
        if self.should_skip():
            self._record_skipped_example(self.formatter)
            self.num_skipped += 1
        else:
            self.execute(context, stdout, stderr)
        return self.num_successes, self.num_failures, self.num_skipped