Django Test with MongoEngine and test database

Problem:

Performing Tests with MongoEngine does not use an alternative database for testing (as the case with Django and relational databases). 

Then why not just connect to the alternative database when performing the tests? Well, that is the problem, the first connection (which is made in the settings.py), and even after disconnecting, when a model (class defined in models.py) is referenced, it will reconnect with the old ('default') database.

If you don't know how to use mongoengine with django, please refer to my other post here

Proposed Workaround:

If you are not interested in the details, you can skip down to the code section

The Document class (that classes defined in models.py inherit from) perform the reconnection with the old database if the _collection is None , and since this is a class variable (not an member of an instance), so we need to set it for each class.

Code:

class NoSQLTestRunner(DjangoTestSuiteRunner):
    def setup_databases(self):
        settings.test_conf['local'] = True
        settings.TEST = True

        self.clearing_db_connection()
        new_db_name = "your_test_db"
        connect(new_db_name)

    def teardown_databases(self, *args):
        db_name = connection._connection_settings['default']['name']
        connection.get_connection().drop_database(db_name)
        connection.disconnect()

    @classmethod
    def clearing_db_connection(cls):
        # disconnect the connection with the db
        connection.disconnect()
        # remove the connection details
        connection._dbs = {}
        connection._connections = {}
        connection._connection_settings = {}
        # getting call classes defined in models.py
        models = pyclbr.readmodule("yourapp.models").keys()
        for class_model in models:
            # delete the collection to prevent automatically connecting with the old db (the live one)
            del globals()[class_model]._collection

Check my other post here on how to use this class

Resources: 
http://stackoverflow.com/questions/15886469/dropping-all-collections-in-mongoengine
https://github.com/MongoEngine/mongoengine/blob/0.8/mongoengine/connection.py
https://github.com/MongoEngine/mongoengine/blob/0.8/mongoengine/document.py
https://docs.djangoproject.com/en/1.7/topics/testing/overview/