Chapter 3 : Testing a Simple Home Page with Unit Tests

"Our First Django App, and Our First Unit Test"

First time use command in "superlists" directory from Chapter 2

python3 manage.py startapp lists

and it create a folder at superlists/lists

     superlists/
     ├── db.sqlite3
     ├── functional_tests.py
     ├── lists
     │   ├── admin.py
     │   ├── __init__.py
     │   ├── migrations
     │   │   └── __init__.py
     │   ├── models.py
     │   ├── tests.py
     │   └── views.py
     ├── manage.py
     └── superlists
         ├── __init__.py
         ├── __pycache__
         ├── settings.py
         ├── urls.py
         └── wsgi.py

and next Unit Testing in Django , Open up the new file at lists/tests.py then edit to this code 

from django.test import TestCase class SmokeTest(TestCase): def test_bad_maths(self): self.assertEqual(1 + 1, 3)

and now let's to run manage.py with this command
python3 manage.py test

Output Result

Then commit this git with this commands
git status # should show you lists/ is untracked git add lists git diff --staged # will show you the diff that you're about to commit git commit -m "Add app for lists, with deliberately failing unit test"

and next , Django’s MVC, URLs, and View Functions

in Django’s workflow goes something like this:

1. An HTTP request comes in for a particular URL.
2. Django uses some rules to decide which view function should deal with the request (this is referred to as resolving the URL).
3. The view function processes the request and returns an HTTP response. 

So we want to test two things:

• Can we resolve the URL for the root of the site (“/”) to a particular view function we’ve made?
• Can we make this view function return some HTML which will get the functional test to pass? 

At first Open up lists/tests.py, and change to something like this:

from django.core.urlresolvers import resolve from django.test import TestCase from lists.views import home_page class HomePageTest(TestCase): def test_root_url_resolves_to_home_page_view(self): found = resolve('/') self.assertEqual(found.func, home_page)

Output Result

" ImportError: cannot import name 'home_page' " 

Solution : We can’t import home_page from lists.views? OK, let’s fix that—and only that. In lists/views.py:
from django.shortcuts import render home_page = None

Let’s run the tests again with this command:
python3 manage.py test

Output Result

 next , Django uses a file called urls.py to define how URLs map to view functions. and change it to same like this:
from django.conf.urls import patterns, include, url from django.contrib import admin urlpatterns = patterns('', # Examples: url(r'^$', 'superlists.views.home', name='home'), # url(r'^blog/', include('blog.urls')), #url(r'^admin/', include(admin.site.urls)), )

Then , Run the unit tests again, with
python3 manage.py test

Output Result

the dot-notation superlists.views.home doesn’t point to a real view. Let’s fix that, by pointing it towards our placeholder home_page object, which is inside lists, not superlists (file : superlists/urls.py)

 

from django.conf.urls import patterns, include, url from django.contrib import admin urlpatterns = patterns('', # Examples: url(r'^$', 'lists.views.home_page', name='home'), )
And run the tests again: Output Result

The unit tests have made the link between the URL / and the home_page = None in lists/views.py, and are now complaining that home_page isn’t a callable; ie, it’s not a function. Now we’ve got a justification for changing it from being None to being an actual function. Every single code change is driven by the tests. Back in lists/views.py:
from django.shortcuts import render # Create your views here. def home_page(): pass

and the last run with command :
python3 manage.py test
Output Result

and TIME TO GIT
git diff # should show changes to urls.py, tests.py, and views.py git commit -am "First unit test and url mapping, dummy view"

NEXT ,Unit Testing a View

Open up lists/tests.py, and add a new test method.
from django.core.urlresolvers import resolve from django.test import TestCase from django.http import HttpRequest from lists.views import home_page class HomePageTest(TestCase): def test_root_url_resolves_to_home_page_view(self): found = resolve('/') self.assertEqual(found.func, home_page) def test_home_page_returns_correct_html(self): request = HttpRequest() response = home_page(request) self.assertTrue(response.content.startswith(b'<html>')) self.assertIn(b'<title>To-Do lists</title>', response.content) self.assertTrue(response.content.endswith(b'</html>'))

Let’s run the unit tests now and see how we get on ... with command :
python3 manage.py test
Output Result

" TypeError: home_page() takes 0 positional arguments but 1 was given "

now,Change code in lists/views.py

 

from django.http import HttpResponse # Create your views here. def home_page(request): return HttpResponse()
Tests again: Output Result

" self.assertTrue(response.content.startswith(b'<html>')) AssertionError: False is not true "

Coding Again Fix return area:
from django.http import HttpResponse # Create your views here. def home_page(request): return HttpResponse('<html>')
 
Tests Again : Output Result

" AssertionError: b'<title>To-Do lists</title>' not found in b'<html>' "

AND Coding Again Fix return area:
from django.http import HttpResponse # Create your views here. def home_page(request): return HttpResponse('<html><title>To-Do lists</title></html>')
 
Tests Again : Output Result

And Time to GIT
git diff # should show our new test in tests.py, and the view in views.py git commit -am "Basic view now returns minimal HTML"

and the last : try to typing git log
git log --oneline

Summary

  Useful Commands and Concepts

Running the Django dev server

python3 manage.py runserver

Running the functional tests

python3 functional_tests.py

Running the unit tests

python3 manage.py test

The unit-test/code cycle

1. Run the unit tests in the terminal.
2. Make a minimal code change in the editor.
3. Repeat!

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credit  :  http://chimera.labs.oreilly.com/books/1234000000754/ch03.html#_urls_py