Python Pyramid - Testing

Writing test scripts which ensure that your code works correctly is considered as a good programming practice. Python ecosystem had a number of testing frameworks, including unittest which is bundled in the standard library. Pytest is a popular testing library. It is a preferred library for Pyramid projects.

We shall use the hello package that we developed earlier while demonstrating the use of PasteDeploy configuration.

First, ensure that the Pyramid environment has PyTest package installed.

pip3 install pytest

Open the setup.py file in hello package and modify it by adding the lines shown in bold.

from setuptools import setup

requires = [
   'pyramid',
   'waitress',
]
dev_requires = ['pytest',]
setup(
   name='hello',
   install_requires=requires,
   extras_require={
      'dev': dev_requires,
   },
   entry_points={
      'paste.app_factory': [
         'main = hello:main'
      ],
   },
)

Here, Pytest is added as the project dependency whenever it is installed (or reinstalled) using following command −

pip3 install -e ".[dev]

Store the following Python code as testing.py in hello package.

import unittest
from pyramid import testing
class HelloTests(unittest.TestCase):
   def test_hello_world(self):
      from . import hello_world
      request = testing.DummyRequest()
      response = hello_world(request)
      self.assertEqual(response.status_code, 200)

To run the tests, use following Pytest command. The output of the test is shown below −

Env\hello>pytest tests.py
========================== test session starts ==========================
platform win32 -- Python 3.10.1, pytest-7.1.2, pluggy-1.0.0
rootdir: E:\tp-pyramid\hello
collected 1 item

tests.py.
   [100%]
 
=========================== 1 passed in 1.12s ===========================

To check if the test fails, induce an error in the test function and run again.

(tp-pyramid) E:\tp-pyramid\hello>pytest tests.py
========================== test session starts ==========================
collected 1 item

tests.py F 
[100%]
=============================== FAILURES ================================
______________________ HelloTests.test_hello_world ______________________
self = <hello.tests.HelloTests testMethod=test_hello_world>
   def test_hello_world(self):
      from . import hello_world
      request = testing.DummyRequest()
      response = hello_world(request)
>     self.assertEqual(response.status_code, 404)
E     AssertionError: 200 != 404

tests.py:13: AssertionError
======================== short test summary info ========================
FAILED tests.py::HelloTests::test_hello_world - AssertionError: 200 != 404
=========================== 1 failed in 1.53s ===========================

Functional Testing

Although Unit tests are popularly used in test-driven development (TDD)approach, for web applications, WebTest is a Python package that does functional testing. We can simulate a full HTTP request against a WSGI application, then test the information in the response.

Example

Let us use the hello project that we had used in the earlier example. Open the setup.py and add WebTest as the project dependency.

from setuptools import setup

requires = [
   'pyramid',
   'waitress',
]
dev_requires = ['pytest','webtest',]
setup(
   name='hello',
   install_requires=requires,
   extras_require={
      'dev': dev_requires,
   },
   entry_points={
      'paste.app_factory': [
         'main = hello:main'
      ],
   },
)

Reinstall the hello package and its new dependency for development mode.

Env\hello>..\scripts\pip3 install -e ".[dev]"

Include a functional test in tests.py file

import unittest
from pyramid import testing

class HelloTests(unittest.TestCase):

   def test_hello_world(self):
      from . import hello_world
      request = testing.DummyRequest()
      response = hello_world(request)
      self.assertEqual(response.status_code, 200)
class HelloFunctionalTests(unittest.TestCase):
   def setUp(self):
      from . import main
      app = main({})
      from webtest import TestApp
      self.testapp = TestApp(app)
   def test_hello_world(self):
      res = self.testapp.get('/', status=200)
      self.assertIn(b'<h1>Hello World!</h1>', res.body)

Output

Finally run Pytest as per the following command −

Env\hello>pytest tests.py
========================== test session starts ==========================
platform win32 -- Python 3.10.1, pytest-7.1.2, pluggy-1.0.0
rootdir: E:\tp-pyramid\hello
collected 2 items
tests.py .. [100%]

=========================== 2 passed in 2.37s ===========================

Tests in Cookiecutter Project

The CookieCutter utility auto-generates the tests package containing functional tests and unit tests. We had earlier used Cookiecutter to build Pyramid project named testproj. In this project, we find tests folder.

Example

The test_functional py contains the following test functions −

from testproj import models

def test_my_view_success(testapp, dbsession):
   model = models.MyModel(name='one', value=55)
   dbsession.add(model)
   dbsession.flush()
   res = testapp.get('/', status=200)
   assert res.body
   
def test_notfound(testapp):
   res = testapp.get('/badurl', status=404)
   assert res.status_code == 404

The test_views.py defines following test functions to test the views −

from testproj import models
from testproj.views.default import my_view
from testproj.views.notfound import notfound_view

def test_my_view_failure(app_request):
info = my_view(app_request)
assert info.status_int == 500

def test_my_view_success(app_request, dbsession):
   model = models.MyModel(name='one', value=55)
   dbsession.add(model)
   dbsession.flush()
   info = my_view(app_request)
   assert app_request.response.status_int == 200
   assert info['one'].name == 'one'
   assert info['project'] == 'testproj'
def test_notfound_view(app_request):
   info = notfound_view(app_request)
   assert app_request.response.status_int == 404
   assert info == {}

Output

These tests are run by the following command −

Env\testproj>Pytest
========================== test session starts ==========================
platform win32 -- Python 3.10.1, pytest-7.1.2, pluggy-1.0.0
rootdir: Env\testproj, configfile: pytest.ini, testpaths: testproj, tests
plugins: cov-3.0.0
collected 5 items

tests\test_functional.py .. [ 40%]
tests\test_views.py ... [100%]
=============== 5 passed, 20 warnings in 6.66s ===============
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