Automated testing is an extremely useful bug-killing tool for the modern Web developer. You can use a collection of tests – a test suite – to solve, or avoid, a number of problems:
Testing a Web application is a complex task, because a Web application is made of several layers of logic – from HTTP-level request handling, to form validation and processing, to template rendering. With Django’s test-execution framework and assorted utilities, you can simulate requests, insert test data, inspect your application’s output and generally verify your code is doing what it should be doing.
The best part is, it’s really easy.
There are two primary ways to write tests with Django, corresponding to the two test frameworks that ship in the Python standard library. The two frameworks are:
Unit tests – tests that are expressed as methods on a Python class
that subclasses unittest.TestCase
or Django’s customized
TestCase
. For example:
import unittest
class MyFuncTestCase(unittest.TestCase):
def testBasic(self):
a = ['larry', 'curly', 'moe']
self.assertEqual(my_func(a, 0), 'larry')
self.assertEqual(my_func(a, 1), 'curly')
Doctests – tests that are embedded in your functions’ docstrings and are written in a way that emulates a session of the Python interactive interpreter. For example:
def my_func(a_list, idx):
"""
>>> a = ['larry', 'curly', 'moe']
>>> my_func(a, 0)
'larry'
>>> my_func(a, 1)
'curly'
"""
return a_list[idx]
Because Django supports both of the standard Python test frameworks, it’s up to you and your tastes to decide which one to use. You can even decide to use both.
For developers new to testing, however, this choice can seem confusing. Here, then, are a few key differences to help you decide which approach is right for you:
doctest
will probably feel
more “pythonic”. It’s designed to make writing tests as easy as possible,
so it requires no overhead of writing classes or methods. You simply put
tests in docstrings. This has the added advantage of serving as
documentation (and correct documentation, at that!). However, while
doctests are good for some simple example code, they are not very good if
you want to produce either high quality, comprehensive tests or high
quality documentation. Test failures are often difficult to debug
as it can be unclear exactly why the test failed. Thus, doctests should
generally be avoided and used primarily for documentation examples only.unittest
framework will probably feel very familiar to
developers coming from Java. unittest
is inspired by Java’s JUnit,
so you’ll feel at home with this method if you’ve used JUnit or any test
framework inspired by JUnit.unittest
framework’s organization around
classes and methods. This makes it easy to abstract common tasks into
common methods. The framework also supports explicit setup and/or cleanup
routines, which give you a high level of control over the environment
in which your test cases are run.unittest
.As unit tests are preferred in Django, we treat them in detail in the Testing Django applications document.
Django and doctests describes Django-specific features when using doctests.
You can also use any other Python test framework, Django provides an API and tools for that kind of integration. They are described in the Using different testing frameworks section of Advanced testing topics.
Apr 12, 2017