you are right here but:
Assert.true(data['device_types']) where data['device_types'] = ['firefoxos'] fails:


>       Assert.true(data['device_types'], 'insufficient data added device_types')

webqa/marketplace-tests/mocks/marketplace_api.py:79: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <class unittestzero.Assert at 0x1a59bb0>, first = ['firefoxos']
msg = 'insufficient data added device_types'

    @classmethod
    def true(self, first, msg=None):
        """
            Asserts that what is given is equal to True
    
            :Args:
             - First object to be tested
             - Message that will be printed if it fails
            """
    
>       assert first is True, msg
E       AssertionError: insufficient data added device_types