Automated testing: Difference between revisions
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import mysite.base.views |
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class TestMultiplication(django.test.TestCase): |
class TestMultiplication(django.test.TestCase): |
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def test_return_one(self): |
def test_return_one(self): |
Revision as of 16:04, 15 March 2011
This is a page about improving or modifying OpenHatch.
We call that "Hacking OpenHatch," and there is a whole category of pages about that.
The purpose of this page is to show you how to write automated tests within the OpenHatch codebase.
If you already know how software testing works, skip to Details specific to OpenHatch.
Tests: An overview
You really should write a test if you add new functionality. That way, you can run:
./bin/mysite test base missions account profile
and you'll see a bunch of dots. Dots mean success.
What a basic test looks like
Imagine this is in mysite/base/views.py:
def multiply(x, y): return x * y
Then this would be in mysite/base/tests.py:
import mysite.base.views class TestMultiplication(django.test.TestCase): def test_return_one(self): # Make a dictionary that should return 1 self.assertEqual(35, mysite.base.views.multiply(7, 5))
Read the official Django testing guide
The official guide on Django testing is quite good. It says:
The best part is, it's really easy.
We use the Django "unit test" style of writing tests.
How to write code that is easy to test
Here are some tips on making code easy to test:
- If you are writing a function, make it accept arguments for its data, rather having it calculate the input itself. For example:
Good
def multiply(x, y): return x * y
Less good
def multiply(x): y = settings.MULTIPLICATION_FACTOR return x * y
It's okay to rely on things like system settings and database content, but in general if your functions are simpler, they are easier to test.
Details specific to OpenHatch
Where to write your tests
In general, add tests to the same Django app as you are editing. For example, if you made changes to base/views.py, then add a test in base/tests.py.
The test files are kind of sprawling. It doesn't really matter where within the tests.py file you add your test. I would suggest adding it to the end of the file.
The OpenHatch test case helper class
In mysite/base/tests.py
About fixtures
If you inherit from TwillTests, you get some data in your database. You can rely on it.
To run your tests
What app did you write your test in? Let's pretend it was in base:
./bin/mysite test base
To run your tests quickly
The normal test runner uses MySQL, and has to do a bunch of database setup and teardown. If you want the tests to run faster, you can use a different settings file that uses an in-memory SQLite database.
./bin/sqlite_mysite test base
The tests will run about five times faster that way.
To run just a few specific tests
./bin/sqlite_mysite test base.Feed base.Unsubscribe.test_unsubscribe_view
The structure here is app.class.method. So if you want to just run your own new test, you can do it that way.
Mocking, patching, and TwillTests
This section is important, but we haven't written it yet. Oops.