validate_file
Description:
Validate an AppStream XML file.
Remember to run as_validator_clear_issues if you do not want previous validation runs to affect the outcome of this validation.
Parameters:
| this | 
           An instance of Validator.  | 
      
| metadata_file | 
           An AppStream XML file.  | 
      
Returns:
| 
           true if file validated successfully.  |