Penesive Random Experiments

Creating a URL Shortener with Flask - Part 3

06 Dec 2015

In this section we dive a bit more deep into looking into how we are going to have some basic functional testing for the application and then we look look into making a config file and finally merge all the changes and make them into our release 0.1

Integration tests

Integration tests are integral part of system development. They make sure that the code works correctly, when we make changes and also validating code merge from several branches. The integration tests in this case will be written our well known unit test framework.

  1. Lets make a testing folder for functional testing

         mkdir testing
     cd testing

  2. We will add a new file called test_basicsite.py in this folder and write the basic setup code

     import unittest
 import sys
 import urllib

 sys.path.append('..')


 class TestBasicUrlShortener(unittest.TestCase):
     def setUp(self):
         self.client = app.test_client()
         self.baseURL = 'http://localhost:5000'

     # this is one of the functions that must be
     # implemented for flask testing.
     def create_app(self):
         app = Flask(__name__)
         app.config['TESTING'] = True
         app.debug = True
         self.baseURL = 'http://localhost:5000'
         return app

  3. To test index we must first send a Get request with the flask client application and check for the return value and the presence of input field and url field in the page that is received

      # Make sure that we have the index page working
 def test_get_to_index(self):
     rv = self.client.get('/')

     assert rv.status_code == 200
     assert 'name=\"url\"' in str(rv.data)
     assert 'input' in str(rv.data)

 # when we send a Get , we need to make sure that
 # it redirects to index
 def test_get_to_urlshortener(self):

     rv =self.client.get('urlshorten')

     self.assertEqual(rv.status_code, 302)
     assert 'localhost'in rv.location

  4. In order to test the post request, we monkey patch the ‘generate_shortURL’ to make sure that it returns a fixed string so that we know the exact string to look for in the response

         # When we send a post we expect it to return a output
 # containing the baseURL and short url
 def test_post_to_urlshortener(self):

     # monkeypatch the generate shortURL so that we know
     # the correct value to expect and perform validation
     # accordingly
     from app.models import urlshortener
     urlshortener.urlShortener.generateShortUrl = self.generate_shortURL
     post_data = {'url': 'http://www.google.com/'}

     rv = self.client.post('/urlshorten',
                           data=post_data,
                           follow_redirects=False)

     self.assertEqual(rv.status_code, 200)
     shorturl = self.baseURL + '/' + self.generate_shortURL()
     assert shorturl in str(rv.data)

     #cleanup so next time it works
     urlshort = urlshortener.urlShortener()
     urlshort.removeUrl(self.generate_shortURL())

  5. Now to check the URL redirect is working correctly we store a short url and then send a get request to make sure that we get a redirect response from our application.

        def test_get_shorturl(self):

         # monkey patch to a particular short url
         # store it in database and then
         # do a get with short url
         from app.models import urlshortener
         urlshortener.urlShortener.generateShortUrl = self.generate_shortURL_for_redirect
         post_data = {'url': 'http://www.google.com/'}
         self.client.post('/urlshorten',
                               data=post_data,
                               follow_redirects=False)

         shorturl = self.baseURL + '/' + self.generate_shortURL_for_redirect()
         rv = self.client.get(shorturl)

         self.assertEqual(rv.status_code, 302)
         self.assertEqual(rv.location, 'http://www.google.com/')

         #cleanup so next time it works
         urlshort = urlshortener.urlShortener()
         urlshort.removeUrl(self.generate_shortURL())

With these, we have covered all the basic integration test cases of our application.

Making a config file for our application

Now all our configuration , we are getting it from our environment variables, but it would be better if we had a uniform configuration file for all our configuration.

  1. we create a new file called config.py which will hold all our configuration in the top level directory.

  2. The code structure looks like below

         ├── LICENSE
     ├── Procfile
     ├── app
     │   ├── __init__.py
     │   ├── __init__.pyc
     │   ├── models
     │   ├── static
     │   ├── templates
     │   ├── views.py
     │   └── views.pyc
     ├── config.py
     ├── config.pyc
     ├── requirements.txt
     ├── run.py
     ├── testing
     │   ├── __init__.py
     │   ├── __init__.pyc
     │   ├── test_basicsite.py
     │   └── test_basicsite.pyc
     ├── tmp

  3. In config.py we add all configuration to be read from the os environment variable and if not available it would not set a default value as below

         import os

     CONNECTION_URI = os.getenv('CONNECTION_STRING','mongodb://localhost:27017/')
     SITE_URL = os.getenv('SITE_URL', 'http://localhost:5000')
     PORT = os.getenv('PORT', 5000)

  4. We import the configuration from all places where we would want to use the configuration as below

         from config import PORT
     app.run(host='0.0.0.0', port=PORT,debug=True)

    This would import the PORT value from the configuration file.

After we have changed the configuration in all the other files where we were doing an os.getenv

  1. Finally we run all the tests again to make sure that nothing is broken

         python -m unittest discover
     ...........
     ----------------------------------------------------------------------
     Ran 11 tests in 0.077s
     OK

Merging code to main

  1. Merge the code from basicURLShortener to master

         $ git checkout master
     Switched to branch 'master'
        
     $ git merge basicUrlShorterner 
     Updating 5c968d2..0f66d0b
     Fast-forward
      .travis.yml                     |  25 +++++++++++++++++++++++++
      app/__init__.py                 |   1 +
      app/models/Makefile             |   7 +++++++
      app/models/MongodbHandler.py    |  15 +++++++++++++++
      app/models/__init__.py          |   0
      app/models/test_urlShortener.py |  90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      app/models/urlshortener.py      |  51 +++++++++++++++++++++++++++++++++++++++++++++++++++
      app/templates/base.html         |  14 ++++++++++++++
      app/templates/index.html        |  23 +++++++++++++++++++++++
      app/views.py                    |  49 ++++++++++++++++++++++++++++++++++++++++++++++++-
      config.py                       |   6 ++++++
      requirements.txt                |   5 +++++
      run.py                          |   4 +++-
      testing/__init__.py             |   0
      testing/test_basicsite.py       | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
      15 files changed, 390 insertions(+), 2 deletions(-)
      create mode 100644 .travis.yml
      create mode 100644 app/models/Makefile
      create mode 100644 app/models/MongodbHandler.py
      create mode 100644 app/models/__init__.py
      create mode 100644 app/models/test_urlShortener.py
      create mode 100644 app/models/urlshortener.py
      create mode 100644 app/templates/base.html
      create mode 100644 app/templates/index.html
      create mode 100644 config.py
      create mode 100644 testing/__init__.py
      create mode 100644 testing/test_basicsite.py
     (venv)Pradheep (master) UrlShortener $

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