Difference between revisions of "Python-Django/C2/Testing-in-Django/English"

• Write tests in Django and
• Run the tests in Django

• Ubuntu Linux OS 16.04
• Python 3.5
• Python 3.4-venv or higher and
• gedit Text Editor

• How to create Models in Django
• If not, then please go through the prerequisite Django tutorials on this website.

• Automated testing is very useful while coding
• We can validate our code during the development stage itself
• It is preferred to write tests in Django using the unit test module

Press CTRl+ALT+T simultaneously

cd my-django [Enter]

Type gedit blog/tests.py & [Enter]

Type gedit <space> blog slash tests dot py <space> ampersand

Highlight

from django.test import TestCase

#Create your tests here.

Here we import TestCase from Django’s test module.

TestCase is a subclass of unit test.

A test case checks whether a given set of inputs leads to an expected set of results.

class BlogTestCase(TestCase): def setUp(self):

Blog.objects.create(name='New Blog')

def test_blog_created(self):

blog = Blog.objects.get(id=1)

name = 'New Blog'

self.assertEqual(blog.name, name)

Highlight class BlogTestCase(TestCase):

It is a subclass of TestCase.

from django.test import TestCase

from blog.models import Blog

def setUp(self):

setUp runs once for every test method to setup clean data.

Highlight Blog.objects.create(name= 'New Blog')

def test_blog_created(self):

Highlight def test_blog_created(self):

Django’s test runner runs these test methods.

blog = Blog.objects.get(id=1)

Highlight id=1

But in complex cases, many blogs are created and deleted.

Highlight self.assertEqual(blog.name, name)

It checks whether the two arguments passed here are equal or not.

Here we have passed the blog name and expected string New Blog.

If the condition does not evaluate as expected, then the test will fail and report the error.

Type python manage.py test blog [Enter]

Creating test database for alias 'default'...

System check identified no issues (0 silenced).

-------------------------------------------------------------

Ran 1 test in 0.002sOKDestroying test database for alias 'default'...

def test_blog_created(self):

blog = Blog.objects.get(id=1)

name = 'New Blog'

self.assertEqual(blog.name, name)

So, let us add another test case for blog app.

def test_was_created_recently(self):

blog = Blog.objects.get(id=1)

is_created_recently = True

self.assertEqual(blog.was_created_recently(), is_created_recently)

blog = Blog.objects.get(id=1)

is_created_recently = True

self.assertEqual (blog.was_created_recently(), is_created_recently)

The method is was_created_recently and it is expected to return True.

So our second argument is a boolean True.

assertEqual function in method test_was_created_recently returns TRUE.

As the two arguments passed are equal, the 2nd test also ran successfully.

We will change the logic of was_created_recently method in this file.

Type gedit blog/models.py & [Enter]

def was_created_recently(self):

return self.created_on <= timezone.now() - timezone.timedelta(days=1)

In the class blog, locate the was_created_recently method.

In the return statement, change the sign greater than to less than.

return self.created_on <= timezone.now() - timezone.timedelta(days=1)

was_created_recently method returns False instead of True.

This shows the power of having tests.

In case anyone modifies the code incorrectly later on, then the tests will help to detect it.

return self.created_on >= timezone.now() - timezone.timedelta(days=1)

def test_was_created_recently(self):

blog = Blog.objects.get(id=1)

self.assertTrue(blog.was_created_recently())

In the function test_was_created_recently, modify the code as shown.

Highlight assertTrue()

Ran 2 tests in 0.003s

OK

https://docs.djangoproject.com/en/2.1/topics/testing/tools/#assertions

• Django TestCase provides assertion methods
• These are useful for testing web applications
• Here is the reference link to the documentation of methods

from django.test import TestCase

from blog.models import Blog

# Create your tests here.

class BlogTestCase(TestCase):

def setUp(self):

Blog.objects.create(name='Blog1')

Blog.objects.create(name='Blog2')

def test_blog_created(self):

blog = Blog.objects.get(id=1)

name = 'New Blog'

self.assertEqual(blog.name, name)

def test_was_created_recently(self):

blog1 = Blog.objects.get(id=1)

blog2 = Blog.objects.get(id=2)

self.assertTrue(blog1.was_created_recently())

self.assertFalse(blog2.was_created_recently())

Blog.objects.create(name='Blog2')

blog2 = Blog.objects.get(id=2)

self.assertFalse(blog2.was_created_recently())

assertFalse

python manage.py test blog.tests.BlogTestCase.test_was_created_recently [Enter]

To do that, we have to write the method name like this.

AssertionError: True is not False

AssertionError raised an error message True is not False.

This is because the was_created_recently returns TRUE and we are expecting FALSE.

def test_was_created_recently(self):

blog1 = Blog.objects.get(id=1)

blog2 = Blog.objects.get(id=2)

self.assertTrue(blog1.was_created_recently())

self.assertTrue(blog2.was_created_recently())

Type python manage.py test blog.tests.BlogTestCase.test_was_created_recently [Enter]

Highlighting the output

• Test runner will create an empty test database with required migrations.
• By default, database will be deleted if all tests are executed or if assertion error is raised.

• SetUp and TearDown methods are run before and after every test respectively.
• This allows you to set up a basic context or environment inside each of the tests.

• SetUp method runs before every test.

• TearDown method will only be called if the setUp() succeeds.

Let us summarize.

• Write tests in Django
• Run tests in Django

• Write a test case for Article model and run the test.

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