- Parameters:
- 
  
    |  | runner | the runner object |  |  | plan | optional plan object |  
 
- Returns:
- 0 on success or non-zero if any tests failed.
Uses the 
runner object to run all the tests described in the 
plan object. If 
plan is NULL, a temporary default plan is created which will result in all the discovered tests being run in testnode tree order.