CODEWITHSUNDEEP
pythonunit-testingtypessqlalchemy
Joey
Joey

Reputation: 1679

Python unit tests: type checking custom class type

I'm writing unit tests as I develop a program. I'm using SQLAlchemy for database processes, so I have a few functions like this:

def create_sqla_engine():
    """ Create and return the SQLA engine """
    mysql_uri = os.environ.get('MYSQL_CONNECTION_URI')
    engine = sqlalchemy.create_engine(mysql_uri)
    return engine

If I do print(type(engine)) I can see that the type is <class 'sqlalchemy.engine.base.Engine'>

...so I want to test if this function works by checking if the type is correct (assuming the type will be None if the create_engine call fails...)

This code is in unittests.py:

class TestDatabase(unittest.TestCase):


    def test_database_create_merkle_sqla_session(self):
        assert type(myprogram_database.create_sqla_engine()) is # ?

How do I check the type of a variable that is a class?

Upvotes: 5

Views: 4023

Answers (1)

mgilson
mgilson

Reputation: 309919

You have a few options here... The easiest is just to check that the object you get back is not None:

self.assertIsNotNone(myprogram_database.create_sqla_engine())

If you actually want to check that the return type is an instance of something else, you can use assertIsInstance:

self.assertIsInstance(myprogram_database.create_sqla_engine(),
                      sqlalchemy.engine.base.Engine)

Upvotes: 8

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