Pylons provides powerful unit testing capabilities for your web application
utilizing paste.fixture
to emulate requests to your web application. You can then ensure that the
response was handled appropriately and that the controller set things up
properly.
To run the test suite for your web application, Pylons utilizes the nose test runner/discovery
package. Running nosetests in your project directory will run all the
tests you create in the tests directory. If you don't have nose installed on
your system, it can be installed via setuptools with:
To avoid conflicts with your development setup, the tests use the test.ini configuration file when run. This means you must configure any databases, etc. in your test.ini file or your tests will not be able to find the database configuration.
Warning
Nose can trigger errors during its attempt to search for doc tests since
it will try and import all your modules one at a time before your app
was loaded. This will cause files under models/ that rely on your app to
be running, to fail.
Pylons 0.9.6.1 and later includes a plugin for nose that loads the app before
the doctests scan your modules, allowing models to be doctested. You can use
this option from the command line with nose:
1 | nosetests --with-pylons=test.ini
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Or by setting up a [nosetests] block in your setup.cfg:
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6 | [nosetests]
verbose=True
verbosity=2
with-pylons=test.ini
detailed-errors=1
with-doctest=True
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Then just run:
1 | python setup.py nosetests
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to run the tests.
First let's create a new project and controller for this example:
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3 | $ paster create -t pylons TestExample
$ cd TestExample
$ paster controller comments
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You'll see that it creates two files when you create a controller. The stub controller, and a test for it under testexample/tests/functional/.
Modify the testexample/controllers/comments.py file so it looks like this:
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10 | from testexample.lib.base import *
class CommentsController(BaseController):
def index(self):
return 'Basic output'
def sess(self):
session['name'] = 'Joe Smith'
session.save()
return 'Saved a session'
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Then write a basic set of tests to ensure that the controller actions are functioning properly, modify testexample/tests/functional/test_comments.py to match the following:
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11 | from testexample.tests import *
class TestCommentsController(TestController):
def test_index(self):
response = self.app.get(url_for(controller='/comments'))
assert 'Basic output' in response
def test_sess(self):
response = self.app.get(url_for(controller='/comments', action='sess'))
assert response.session['name'] == 'Joe Smith'
assert 'Saved a session' in response
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Run nosetests in your main project directory and you should see them all pass:
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5 | ..
----------------------------------------------------------------------
Ran 2 tests in 2.999s
OK
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Unfortunately, a plain assert does not provide detailed information about the results of an assertion should it fail, unless you specify it a second argument. For example, add the following test to the test_sess function:
1 | assert response.session.has_key('address') == True
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When you run nosetests you will get the following, not-very-helpful result:
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14 | .F
======================================================================
FAIL: test_sess (testexample.tests.functional.test_comments.TestCommentsController)
----------------------------------------------------------------------
Traceback (most recent call last):
File "~/TestExample/testexample/tests/functional/test_comments.py", line 12, in test_sess
assert response.session.has_key('address') == True
AssertionError:
----------------------------------------------------------------------
Ran 2 tests in 1.417s
FAILED (failures=1)
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You can augment this result by doing the following:
1 | assert response.session.has_key('address') == True, "address not found in session"
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Which results in:
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14 | .F
======================================================================
FAIL: test_sess (testexample.tests.functional.test_comments.TestCommentsController)
----------------------------------------------------------------------
Traceback (most recent call last):
File "~/TestExample/testexample/tests/functional/test_comments.py", line 12, in test_sess
assert response.session.has_key('address') == True
AssertionError: address not found in session
----------------------------------------------------------------------
Ran 2 tests in 1.417s
FAILED (failures=1)
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But detailing every assert statement could be time consuming. Our TestController subclasses the standard Python unittest.TestCase class, so we can use utilize its helper methods, such as assertEqual, that can automatically provide a more detailed AssertionError. The new test line looks like this:
1 | self.assertEqual(response.session.has_key('address'), True)
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Which provides the more useful failure message:
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8 | .F
======================================================================
FAIL: test_sess (testexample.tests.functional.test_comments.TestCommentsController)
----------------------------------------------------------------------
Traceback (most recent call last):
File "~/TestExample/testexample/tests/functional/test_comments.py", line 12, in test_sess
self.assertEqual(response.session.has_key('address'), True)
AssertionError: False != True
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Pylons will provide several additional attributes for the paste.fixture response object that let you access various objects that were created during the web request:
- session
- Session object
- req
- Request object
- c
- Object containing variables passed to templates
- g
- Globals object
To use them, merely access the attributes of the response after you've used
a get/post command:
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3 | response = app.get('/some/url')
assert response.session['var'] == 4
assert 'REQUEST_METHOD' in response.req.environ
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Note
The paste.fixture response object already has a TestRequest object
assigned to it, therefore Pylons assigns its request object to the
response as req.
Paste's fixture testing allows you to designate your own objects that you'd
like to access in your tests. This powerful functionality makes it easy to
test the value of objects that are normally only retained for the duration of
a single request.
Before making objects available for testing, its useful to know when your
application is being tested. Paste will provide an environ variable called
paste.testing that you can test for the presence and truth of so that your
application only populates the testing objects when it has to.
Populating the paste.fixture response object with your objects is done by
adding them to the environ dict under the key paste.testing_variables.
Pylons creates this dict before calling your application, so testing for its
existence and adding new values to it is recommended. All variables assigned
to the paste.testing_variables dict will be available on the response
object with the key being the attribute name.
Example:
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27 | # testexample/lib/base.py
from pylons import c, g, cache, request, response, session
from pylons.controllers import WSGIController
from pylons.decorators import jsonify, rest, validate
from pylons.templating import render, render_response
from pylons.helpers import abort, redirect_to, etag_cache
import testexample.models as model
import testexample.helpers as h
class BaseController(WSGIController):
def __call__(self, environ, start_response):
# Create a custom email object
email = MyCustomEmailObj()
email.name = 'Fred Smith'
if 'paste.testing_variables' in request.environ:
request.environ['paste.testing_variables']['email'] = email
return WSGIController.__call__(self, environ, start_response)
# testexample/tests/functional/test_controller.py
from testexample.tests import *
class TestCommentsController(TestController):
def test_index(self):
response = self.app.get(url_for(controller='/'))
assert response.email.name == 'Fred Smith'
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Posted by
Is it possible to pass Python objects to the tested controller from an unit test? I found only a way to pass strings using the extra_environ or in the request string. Passing objects would make testing certain type of controllers easier.