Python-Django/C2/Testing-in-Django/English

Django/C2/Testing in Django/English

Title of script: Testing in Django

Keywords: Video tutorial, Django write test, Django run test

Visual cue	Narration
Slide: Writing Tests in Django	Hello and welcome to the spoken tutorial on “Testing in Django“
Slide: Learning Objectives	In this tutorial, we will learn to Write tests in Django and Run the tests in Django
Slide: System Requirements	To record this tutorial, I am using Ubuntu Linux OS 16.04 Python 3.5 Python 3.4-venv or higher and gedit Text Editor
Slide: Prerequisites	To follow this tutorial, you need to know How to create Models in Django If not, then please go through the prerequisite Django tutorials on this website.
Slide: Testing in Django	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
Open a Terminal window Press CTRl+ALT+T simultaneously	Let us open the terminal by pressing Ctrl, Alt and T keys simultaneously on the keyboard.
[Terminal] cd my-django [Enter]	Using the cd command, go to the folder my hyphen django
[Terminal] Type: source myapp_env/bin/activate and press Enter	Activate the virtual environment.
[Terminal] cd mysite and Press Enter	Now go to the mysite folder using cd command
	Here onwards, please remember to press the Enter key after typing each command.
[Terminal] Type gedit blog/tests.py & [Enter]	Let us write the test case for our blog app. Type gedit <space> blog slash tests dot py <space> ampersand
[tests.py] Highlight from django.test import TestCase #Create your tests here.	We are now in tests.py file 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.
[tests.py] Type: 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)	Let us now add a class BlogTestCase as shown here.
[tests.py] Highlight class BlogTestCase(TestCase):	Here, we have created a class BlogTestCase to test our Blog model. It is a subclass of TestCase.
[tests.py] Highlight from django.test import TestCase	class TestCase is used for writing tests in Django.
[tests.py] Type: from blog.models import Blog	So, after the TestCase import, we will import the Blog model.
[tests.py] Highlight def setUp(self):	Whenever the test runs, first it will call the setUp method. setUp runs once for every test method to setup clean data.
[tests.py] Highlight Blog.objects.create(name= 'New Blog')	So in the setUp, a blog is created.
[tests.py] Highlight def test_blog_created(self):	Here a method test_blog_created is defined to test the blog which is created.
[tests.py] Highlight def test_blog_created(self):	class TestCase methods begins with the name test. Django’s test runner runs these test methods.
[tests.py] Highlight blog = Blog.objects.get(id=1)	Here we get the blog object that we created in the setUp().
[tests.py] Highlight id=1	ids are uniquely generated for each blog. But in complex cases, many blogs are created and deleted.
[tests.py] Highlight name = 'New Blog'	Let’s define a variable as string “New Blog”.
[tests.py] Highlight self.assertEqual(blog.name, name)	assertEqual is a method provided by TestCase. 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.
Highlight the complete code	Now, we have added a TestCase.
Press Ctrl+S	Save the file.
Only narration	Let us now run the test.
Switch to Terminal	Switch to the terminal.
[Terminal] Type python manage.py test blog [Enter]	Then type: python <space> manage dot py <space> test <space> blog
[Terminal] Highlight python manage.py test blog	This command looks for all the files that starts with test in the app.
[Terminal] Output: Creating test database for alias 'default'... System check identified no issues (0 silenced). ------------------------------------------------------------- Ran 1 test in 0.002sOKDestroying test database for alias 'default'...	Here, we can see the output.
[tests.py] Highlight def test_blog_created(self): blog = Blog.objects.get(id=1) name = 'New Blog' self.assertEqual(blog.name, name)	Test ran successfully as the first and second arguments which were passed, are equal.
Switch to blog/tests.py	The Test we ran is very minor. So, let us add another test case for blog app.
[tests.py]Type: 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)	Add a method in BlogTestCase as shown here.
[tests.py] Highlight blog = Blog.objects.get(id=1)	Get the Blog object to test by passing the id and assigning it to the variable blog.
[tests.py] Highlight is_created_recently = True	Assign the value True to is_created_recently
[tests.py] Highlight self.assertEqual (blog.was_created_recently(), is_created_recently)	Here in assertEqual the first argument is a method call. The method is was_created_recently and it is expected to return True. So our second argument is a boolean True.
Press Ctrl+S	Save the file.
Switch to Terminal	Switch to the terminal.
[Terminal] Type python manage.py test blog [Enter]	Now, recall the previous command to run the test.
[Terminal] Output: Ran 2 tests in 0.003s	The output says, Ran 2 tests. assertEqual function in method test_was_created_recently returns TRUE. As the two arguments passed are equal, the 2nd test also ran successfully.
[Terminal]	Next open the models.py file. We will change the logic of was_created_recently method in this file.
[Terminal] Type gedit blog/models.py & [Enter]	Type gedit <space> blog slash models dot py <space> ampersand
[models.py]Type: def was_created_recently(self): return self.created_on <= timezone.now() - timezone.timedelta(days=1)	We are now in models.py file. In the class blog, locate the was_created_recently method. In the return statement, change the sign greater than to less than.
[models.py] Highlight return self.created_on <= timezone.now() - timezone.timedelta(days=1)	Since the blog object was not created recently, the method returns False.
Press Ctrl+S	Save the file.
Switch to Terminal	Switch to the terminal.
[Terminal] Type python manage.py test blog [Enter]	And run the test again.
[Terminal] Output: AssertionError: False!= True	The output shows an assertion error. 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.
Switch to models.py	Switch back to models.py file to revert the changes.
[models.py] Highlight return self.created_on >= timezone.now() - timezone.timedelta(days=1)	Locate method was_created_recently under Class Blog. And change the less than sign to greater than.
Press Ctrl+S	Save the file.
[tests.py] Type: def test_was_created_recently(self): blog = Blog.objects.get(id=1) self.assertTrue(blog.was_created_recently())	Switch to the tests.py file. In the function test_was_created_recently, modify the code as shown.
[tests.py] Highlight assertTrue()	Here assertTrue method is used to check the test the expression is TRUE
Press Ctrl+S	Save the file.
Switch to Terminal	Switch to the terminal.
[Terminal] Type python manage.py test blog [Enter]	And run the test app.
[Terminal] Highlight Ran 2 tests in 0.003s OK	The test ran without any errors, satisfying the given condition.
Slide: Assertions	Django TestCase provides custom assertion methods These are useful for testing web applications Here is the reference link to the documentation of methods https://docs.djangoproject.com/en/2.1/topics/testing/tools/#assertions
Switch to blog/tests.py	Switch to tests.py file.
[tests.py] 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())	Modify the code as shown here.
[tests.py] Highlight Blog.objects.create(name='Blog2')	Here, we created a blog object blog 2 in setUp() method.
[tests.py] Highlight blog2 = Blog.objects.get(id=2)	Here we get the blog object 2 that we created in the setUp().
[tests.py] Highlight self.assertFalse(blog2.was_created_recently())	Let us use assertFalse method for our blog object 2 in our was_created_recently function.
[tests.py] Highlight assertFalse	Here assertFalse method is checks the test the expression is False
Press Ctrl+S	Save the file.
Switch to terminal	Switch to terminal
[Terminal]Type python manage.py test blog.tests.BlogTestCase.test_was_created_recently [Enter]	Let us now run a particular test case. To do that, we have to write the method name like this:
[Terminal] Highlight AssertionError: True is not False	On execution, we can see the output for the test case. AssertionError raised an error message True is not False. This is because the was_created_recently returns TRUE and we are expecting FALSE.
Switch to blog/tests.py	Switch to tests.py file to correct the assertion error.
[tests.py] 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())	Change assertFalse to assertTrue.
Press Ctrl+S	Save the file.
Switch to terminal	Switch to terminal.
[Terminal] Type python manage.py test blog.tests.BlogTestCase.test_was_created_recently [Enter]	And execute the specific test case again.
[Terminal] Highlighting the output	The test ran successfully without any assertion errors.
Switch to Terminal	This is how we should perform the testing in Django.
[Terminal] Type deactivate [Enter]	let us now deactivate the virtual environment.
Slide: Test Database	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.
Slide: SetUp and Teardown methods	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.
Slide: SetUp method	SetUp method runs before every test.
Slide: TearDown method	TearDown method will only be called if the setUp() succeeds.
	With this, we come to the end of this tutorial. Let us summarize.
Slide: Summary	In this tutorial, we have learnt to Write tests in Django Run tests in Django
Slide: Assignment	As an assignment, Write a test case for Article model and run the test.
Slide: About Spoken Tutorial project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
Slide: Spoken Tutorial workshops	TheSpoken Tutorial Projectteam conducts workshops and gives certificates. For more details, please write to us.
Slide: Forum for specific questions:	Please post your timed queries in this Forum.
Slide: FOSSEE to answer questions	Please post your general or technical questions in this Forum.
Slide: Acknowledgement	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. More information on this mission is available at this link.
Slide: Thanks Slide	This script has been contributed by Thiagarajar College of Engineering and the FOSSEE Project, IIT Bombay. The video has been recorded by Praveen from Spoken Tutorial Project, IIT Bombay. Thanks for watching.

Contributors and Content Editors

Nancyvarkey, Pravin1389