Defining multiple unique keys

I would like to define multiple unique tests on 1 model but got following compilation error :
Running with dbt=0.20.1
Encountered an error:
Compilation Error
Invalid test config given in models/tableau/zrshop.yml:
test definition dictionary must have exactly one key, got [(‘unique’, None), (‘severity’, ‘error’)] instead (2 keys)
@: UnparsedNodeUpdate(original_file_path='model…ne)