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fixing some wording issues on the testing page

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Signed-off-by: Armin Ronacher <armin.ronacher@active-4.com>
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matt swanson 2011-03-13 17:18:19 -09:00 • committed by Armin Ronacher
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docs/testing.rst
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@ -5,26 +5,23 @@ Testing Flask Applications
**Something that is untested is broken.**
Not sure where that is coming from, and it's not entirely correct, but
also not that far from the truth. Untested applications make it hard to
The origin of this quote is unknown and while it is not entirely correct, it is also
not far from the truth. Untested applications make it hard to
improve existing code and developers of untested applications tend to
become pretty paranoid. If an application has automated tests, you can
safely change things, and you will instantly know if your change broke
something.
safely make changes and instantly know if anything breaks.
Flask gives you a couple of ways to test applications. It mainly does
that by exposing the Werkzeug test :class:`~werkzeug.test.Client` class to your
code and handling the context locals for you. You can then use that with
your favourite testing solution. In this documentation we will use the
:mod:`unittest` package that comes preinstalled with each Python
installation.
Flask provides a way to test your application by exposing the Werkzeug
test :class:`~werkzeug.test.Client` and handling the context locals for you.
You can then use that with your favourite testing solution. In this documentation
we will use the :mod:`unittest` package that comes pre-installed with Python.
The Application
---------------
First we need an application to test for functionality. For the testing
we will use the application from the :ref:`tutorial`. If you don't have
that application yet, get the sources from `the examples`_.
First, we need an application to test; we will use the application from
the :ref:`tutorial`. If you don't have that application yet, get the
sources from `the examples`_.
.. _the examples:
http://github.com/mitsuhiko/flask/tree/master/examples/flaskr/
@ -32,8 +29,8 @@ that application yet, get the sources from `the examples`_.
The Testing Skeleton
--------------------
In order to test that, we add a second module (
`flaskr_tests.py`) and create a unittest skeleton there::
In order to test the application, we add a second module
(`flaskr_tests.py`) and create a unittest skeleton there::
import os
import flaskr
@ -55,13 +52,14 @@ In order to test that, we add a second module (
unittest.main()
The code in the :meth:`~unittest.TestCase.setUp` method creates a new test
client and initializes a new database. That function is called before
each individual test function. To delete the database after the test, we
close the file and remove it from the filesystem in the
:meth:`~unittest.TestCase.tearDown` method. What the test client does is
give us a simple interface to the application. We can trigger test
requests to the application, and the client will also keep track of cookies
for us.
client and initializes a new database. This function is called before
each individual test function is run. To delete the database after the
test, we close the file and remove it from the filesystem in the
:meth:`~unittest.TestCase.tearDown` method.
This test client will give us a simple interface to the application. We can
trigger test requests to the application, and the client will also keep track
of cookies for us.
Because SQLite3 is filesystem-based we can easily use the tempfile module
to create a temporary database and initialize it. The
@ -70,7 +68,7 @@ low-level file handle and a random file name, the latter we use as
database name. We just have to keep the `db_fd` around so that we can use
the :func:`os.close` function to close the file.
If we now run that test suite, we should see the following output::
If we now run the test suite, we should see the following output::
$ python flaskr_tests.py
@ -79,17 +77,17 @@ If we now run that test suite, we should see the following output::
OK
Even though it did not run any tests, we already know that our flaskr
Even though it did not run any actual tests, we already know that our flaskr
application is syntactically valid, otherwise the import would have died
with an exception.
The First Test
--------------
Now we can add the first test. Let's check that the application shows
"No entries here so far" if we access the root of the application (``/``).
For that we modify our created test case class so that it looks like
this::
Now it's time to start testing the functionality of the application.
Let's check that the application shows "No entries here so far" if we
access the root of the application (``/``). To do this, we add a new
test method to our class, like this::
class FlaskrTestCase(unittest.TestCase):
@ -106,13 +104,14 @@ this::
rv = self.app.get('/')
assert 'No entries here so far' in rv.data
Test functions begin with the word `test`. Every function named like that
will be picked up automatically. By using `self.app.get` we can send an
HTTP `GET` request to the application with the given path. The return
value will be a :class:`~flask.Flask.response_class` object. We can now
use the :attr:`~werkzeug.wrappers.BaseResponse.data` attribute to inspect the
return value (as string) from the application. In this case, we ensure
that ``'No entries here so far'`` is part of the output.
Notice that our test functions begin with the word `test`; this allows
:mod:`unittest` to automatically identify the method as a test to run.
By using `self.app.get` we can send an HTTP `GET` request to the application with
the given path. The return value will be a :class:`~flask.Flask.response_class` object.
We can now use the :attr:`~werkzeug.wrappers.BaseResponse.data` attribute to inspect
the return value (as string) from the application. In this case, we ensure that
``'No entries here so far'`` is part of the output.
Run it again and you should see one passing test::
@ -123,18 +122,14 @@ Run it again and you should see one passing test::
OK
Of course you can submit forms with the test client as well, which we will
use now to log our user in.
Logging In and Out
------------------
The majority of the functionality of our application is only available for
the administrative user, so we need a way to log our test client in to the
application and out of it again. For that we fire some requests to the
login and logout pages with the required form data (username and
password). Because the login and logout pages redirect, we tell the
client to `follow_redirects`.
the administrative user, so we need a way to log our test client in and out
of the application. To do this, we fire some requests to the login and logout
pages with the required form data (username and password). And because the
login and logout pages redirect, we tell the client to `follow_redirects`.
Add the following two methods to your `FlaskrTestCase` class::
@ -147,7 +142,7 @@ Add the following two methods to your `FlaskrTestCase` class::
def logout(self):
return self.app.get('/logout', follow_redirects=True)
Now we can easily test if logging in and out works and that it fails with
Now we can easily test that logging in and out works and that it fails with
invalid credentials. Add this new test to the class::
def test_login_logout(self):
@ -163,7 +158,7 @@ invalid credentials. Add this new test to the class::
Test Adding Messages
--------------------
Now we can also test that adding messages works. Add a new test method
We should also test that adding messages works. Add a new test method
like this::
def test_messages(self):
@ -189,7 +184,7 @@ Running that should now give us three passing tests::
OK
For more complex tests with headers and status codes, check out the
`MiniTwit Example`_ from the sources. That one contains a larger test
`MiniTwit Example`_ from the sources which contains a larger test
suite.
@ -200,12 +195,12 @@ suite.
Other Testing Tricks
--------------------
Besides using the test client we used above, there is also the
:meth:`~flask.Flask.test_request_context` method that in combination with
the `with` statement can be used to activate a request context
temporarily. With that you can access the :class:`~flask.request`,
Besides using the test client as shown above, there is also the
:meth:`~flask.Flask.test_request_context` method that can be used
in combination with the `with` statement to activate a request context
temporarily. With this you can access the :class:`~flask.request`,
:class:`~flask.g` and :class:`~flask.session` objects like in view
functions. Here's a full example that showcases this::
functions. Here is a full example that demonstrates this approach::
app = flask.Flask(__name__)
@ -213,7 +208,8 @@ functions. Here's a full example that showcases this::
assert flask.request.path == '/'
assert flask.request.args['name'] == 'Peter'
All the other objects that are context bound can be used the same.
All the other objects that are context bound can be used in the same
way.
If you want to test your application with different configurations and
there does not seem to be a good way to do that, consider switching to
@ -225,7 +221,7 @@ Keeping the Context Around
.. versionadded:: 0.4
Sometimes it can be helpful to trigger a regular request but keep the
Sometimes it is helpful to trigger a regular request but still keep the
context around for a little longer so that additional introspection can
happen. With Flask 0.4 this is possible by using the
:meth:`~flask.Flask.test_client` with a `with` block::
@ -236,9 +232,10 @@ happen. With Flask 0.4 this is possible by using the
rv = c.get('/?tequila=42')
assert request.args['tequila'] == '42'
If you would just be using the :meth:`~flask.Flask.test_client` without
If you were to use just the :meth:`~flask.Flask.test_client` without
the `with` block, the `assert` would fail with an error because `request`
is no longer available (because used outside of an actual request).
Keep in mind however that :meth:`~flask.Flask.after_request` functions
are already called at that point so your database connection and
is no longer available (because you are trying to use it outside of the actual request).
However, keep in mind that any :meth:`~flask.Flask.after_request` functions
are already called at this point so your database connection and
everything involved is probably already closed down.