pyrsatest 1.3.1

Unit testing utilities for Pyramid applications

Pyramid SQLAlchemy unit testing utilities

A package which provides Python classes that enables SQLAlchemy functionality to be mocked in unit tests for an application written in Pyramid or a similar framework.

These utilities are designed to help in writing unit tests for situations where test setup is overly time-consuming or otherwise problematic. This may include the requirement for extensive amounts of request data for which queries filter upon, or for an extensive variety of related records to be created due to complex database schemas etc.

In mocking and explicitly setting return values for SQLAlchemy queries, the appreciation of control flow is made easier in many cases. Note that in using the provided objects, such as mocking SQLAlchemy ORM queries through MockDbSession, whether queries are written correctly or return results are as expected is left untested.

The source for this project is available here.

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Available functionality and example usage

MockModel

Useful for representing objects such as ORM query results. Desired attributes are set in their construction from keywords arguments.

>>> from pyrasatest import MockModel
>>> mm = MockModel(name='Paul', age='34')
>>> print(f'My name is {mm.name} and my age is {mm.age}')
My name is Paul and my age is 34

For testing code which accesses an SQLAlchemy query result object using indexing as an alternative to dotted attribute lookup (i.e. namedtuple-like access), values will be returned according to ordering of kwargs which are passed to the constructor, for example:

>>> mock_model = MockModel(foo='0', bar='1')
>>> mock_model[0]
'0'

For Python versions before 3.6, where dictionaries have no ordering, the following method should be used to specify return values from indexing:

>>> mock_model.set_result_items(['foo_value', 'bar_value'])
>>> mock_model[0]
'foo_value'

LazyAttrMockModel is similar to MockModel except that in the case of a failed attribute lookup, it will return None instead of raising AttributeError.

MockRequest

MockRequest objects, which inherit from Pyramid.testing.DummyRequest, have an instance of MockDbSession as an attribute. Database interactions, which would usually involve an SQLAlchemy session instance through request.dbsession, will use an instance of MockDbSession instead. This can be customized accordingly, usage is demonstrated below.

MockDbSession

To set query results more generally, see MockQuery usage notes. Query results can be set in a specific manner, according to the model or model property which is the first positional argument passed to dbession.query in the unit of code being tested. The following view callable has multiple dbession.query calls:

class ExampleView:
    def __init__(self, request):
        self.request = request

    @view_config(route_name='order_info', renderer='../templates/mytemplate.mako')
    def get_order_info(self):
        try:
            order = self.request.dbsession.query(models.Order).filter(
                models.Order.id == self.request.params.get('order_id')).one()
            a = type(order)
        except exc.SQLAlchemyError:
            return {'status': 'order not found'}

        try:
            product_id = self.request.dbsession.query(models.Product.id).filter(
                models.Product.number == self.request.params.get('product_number')).one()[0]
        except exc.SQLAlchemyError:
            return {'status': f'product not found for order id {order.id}'}

        try:
            acc_name = self.request.dbsession.query(models.Account.name).filter(
                models.Account.id == self.request.params.get('account_id')).one()[0]
        except exc.SQLAlchemyError:
            return {'status': f'account not found for order id {order.id}'}

        return {
            'status': 'ok',
            'order_number': order.number,
            'product_id': product_id,
            'account_name': acc_name,
        }

The following tests for the above demonstrates the setting of return values for specific queries:

...
from pyrasatest import MockModel, MockRequest
from sqlalchemy import exc

from app.models import Account, Order, Product
from app.views.default import ExampleView

class ExampleViewTestCase(unittest.TestCase):
    def setUp(self):
        self.view = ExampleView(MockRequest())

    def test_get_order_info_order_not_found(self):
        self.view.request.dbsession.query_return_values = {
            Order: exc.SQLAlchemyError
        }
        self.assertEqual(
            {'status': 'order not found'},
            self.view.get_order_info()
        )

    def test_get_order_info_product_not_found(self):
        mock_order = MockModel(id=12)
        self.view.request.dbsession.query_return_values = {
            # MockQuery can be used as a value, this allows customization
            # Order: MockQuery(one_=mock_order) 
            Order: mock_order,
            Product.id: exc.SQLAlchemyError
        }
        self.assertEqual(
            {'status': f'product not found for order id {mock_order.id}'},
            self.view.get_order_info()
        )

    def test_get_order_info_account_not_found(self):
        mock_order = MockModel(id=12)
        self.view.request.dbsession.query_return_values = {
            Order: mock_order,
            Product.id: MockModel(id=25),
            Account.name: exc.SQLAlchemyError
        }
        self.assertEqual(
            {'status': f'account not found for order id {mock_order.id}'},
            self.view.get_order_info()
        )

    def test_get_order_info(self):
        mock_order = MockModel(id=12, number=5)
        mock_product = MockModel(id=25)
        mock_account = MockModel(name='test_acc')
        query_return_values = {
            Order: mock_order,
            Product.id: mock_product,
            Account.name: mock_account
        }
        self.view.request.dbsession.query_return_values = query_return_values
        expected_output = {
            'status': 'ok',
            'order_number': mock_order.number,
            'product_id': mock_product[0],
            'account_name': mock_account[0],
        }
        self.assertEqual(expected_output, self.view.get_order_info())

PartialMockDbSession

Subclasses MockDbSession and makes it so ORM query mocking is restricted to only the specified queries. In creating an instance, a test database session instance must be provided, as well as a dict whose data specifies which queries to mock along with desired return values.

If a dbsession.query call contains no key matching the first positional argument passed to it, then that call will not be mocked. Otherwise it is used as the return value from any chained .one(), .first() or .all() calls, or an Exception raised if the value is an Exception class.

In the following example, suppose a unit of code being tested contained the following dbsession.query calls:

accounts = request.dbsession.query(Account).filter(...).one()
supplier = request.dbsession.query(Supplier, Country.id).filter(...).one()
products = request.dbsession.query(Product.id).filter(...).all()

Then to selectively mock the last two calls (and leave the first one unmocked), PartialMockDbSession can be used as follows:

...
from pyramid.testing import DummyRequest
from pyrasatest import PartialMockDbSession
from sqlalchemy import exc

from app.models import Account, Supplier, Product
from app.models.meta import Base
from app.views import ExampleView

class ExampleViewTestCase(unittest.TestCase):
    @classmethod
    def setUpClass(cls):
        engine = create_engine('sqlite:///:memory:')
        cls.session = scoped_session(sessionmaker(bind=engine))
        Base.metadata.create_all(engine)
        request = DummyRequest()
        request.dbsession = cls.session
        cls.view = ExampleView(request)
        acc1 = Account(name='acc1', number='123')
        ...


    def test_get_account_and_product_number_with_mocked_product_query(self):
        self.view.request.params = {'account_id': self.accounts[0].id}
        mock_product = MockModel(number=32)
        self.view.request.dbsession = PartialMockDbSession(
            query_return_values={Product.id: mock_product},
            dbsession=self.session
        )
        acc_name = self.accounts[0].name
        self.assertEqual(
            {'account_name': acc_name, 'product_number': mock_product[0]},
            self.view.get_account_and_product_number()
        )

MockQuery

As defined in MockQuery.__init__, a number of keywords arguments have meaning which affect behavior on subsequent method calls.

To set returns values for queries which end in .first() and .one() as in the following view callable:

class ExampleView:
    def __init__(self, request):
        self.request = request

    @view_config(route_name='account_info', renderer=template_path)
    def get_account_info(self):
        account = self.request.dbsession.query(models.Account).filter(
            models.Account.id == self.request.params.get('account_id')
        ).first()
        if not account:
            try:
                account = self.request.dbsession.query(models.Account).filter(
                    models.Account.name == 'guest'
                ).one()
            except exc.SQLAlchemyError:
                return {}
        return {'account_name': account.name, 'account_number': account.number}

Instantiate MockQuery with the appropriate keyword arguments and assign to self.request.dbsession as in the following example. Usage also involves testing of a condition where exc.SQLAlchemy is raised:

from pyrasatest import MockModel, MockQuery
from sqlalchemy import exc

from app.views.default import ExampleView

class ExampleViewTestCase(unittest.TestCase):
    def setUp(self):
        self.view = ExampleView(MockRequest()) 

    def test_get_account_info(self):
        mock_acc = MockModel(name='Abc', number='123')
        self.view.request.dbsession.return_value = MockQuery(first_=mock_acc)
        self.assertEqual(
            {'account_name': mock_acc.name, 'account_number': mock_acc.number},
            self.view.get_account_info()
        )

    def test_get_account_info_account_not_found(self):
        self.view.request.dbsession.return_value = MockQuery(
            first_=None,
            raise_exc=exc.SQLAlchemyError
        )
        self.assertEqual({}, self.view.get_account_info())

For query results returned by .all(), where the code being tested iterates over the result, pass in the desired return value in a manner similar to:
MockQuery(all_=['result1', 'result2'])

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Installation

To install the package you can use pip:

$ pip install pyrasatest