pyrsatest 1.2.1

Unit testing utilities for Pyramid applications

Pyramid SQLAlchemy unit testing utilities

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

In mocking interactions with the database layer, time and effort expenditure associated with test setup can be reduced. By setting explicit return values for ORM queries, control flow is simplified, both in the writing tests and the reading of tests. It can also save time in writing tests by avoiding the need to setup params used in such queries, such as in filtering based upon request parameters.

Note that in using the provided objects, for instance in mocking SQLAlchemy ORM queries through MockDbSession, whether queries are written correctly or return results are as expected is left untested. (Through a configuration file, however, tests that mock such interactions using a patch decorator can be selectively unpatched.)

The package written to assist unit testing of applications which use SQLAlchemy as a database backend, and a framework such as Pyramid, within which models have no direct awareness of the database. For Pyramid, where database interactions made within view callables are carried out through request.dbsession, the replacement mock database session functionality is provided accordingly. MockDbSession is still otherwise available to import and use in the creation of test objects.

[The source for this project is available here][https://github.com/paulosjd/pyrasatest].

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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

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. In passing a MockRequest instance to a Pyramid view callable, database interactions which would usually involve an SQLAlchemy session instance through request.dbsession will instead use MockDbSession. Usage is demonstrated in examples below.

MockDbSession

For testing code which accesses an SQLAlchemy object Result which uses indexing as alternative to dotted attribute lookup (i.e. allow namedtuple-like interface), 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'

To set query results more generally, use MockQuery as described below. Query results can be specified according to the model or model property which is the first positional argument passed to dbession.query. The following view callable has multiple dbession.query calls:

class OrderInfoView:
    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:

import unittest

from pyrasatest import MockModel, MockRequest
from sqlalchemy import exc

from ..models import Account, Order, Product
from ..views.default import OrderInfoView


class OrderInfoViewTestCase(unittest.TestCase):
    def setUp(self):
        self.view = OrderInfoView(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 = {
            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())

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 OrderInfoView:
    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 ..views.default import AccountInfoView


class AccountInfoViewTestCase(unittest.TestCase):
    def setUp(self):
        self.view = AccountInfoView(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']).