NYU DevOps lab on Test Driven Development

One of my favorite quotes is:

“If it's worth building, it's worth testing. If it's not worth testing, why are you wasting your time working on it?”

As Software Engineers we need to have the discipline to ensure that our code works as expected and continues to do so regardless of any changes, refactoring, or the introduction of new functionality.

This lab introduces Test Driven Development using PyUnit and nose. It also explores the use of using RSpec syntax with Python through the introduction of noseOfYeti and expects as plug-ins that make test cases more readable.

This lab also demonstrates how to create a simple RESTful service using Python Flask and SQLite. The resource model is persistences using SQLAlchemy to keep the application simple. It's purpose is to show the correct API and return codes that should be used for a REST API.

Note: All of the code is in one file server.py to make it easier to teach. In a "real" application you would separate out the code into several modules.

The easiest way to use this lab is with Vagrant and VirtualBox. if you don't have this software the first step is down download and install it.

Download VirtualBox

Download Vagrant

Then all you have to do is clone this repo and invoke vagrant:

git clone https://github.com/nyu-devops/ab-flask-tdd.git
cd lab-flask-tdd
vagrant up
vagrant ssh
cd /vagrant

You can now run nosetests to run the tests.

Run the tests using nose

$ nosetests

Nose is configured to automatically include the flags --with-spec --spec-color so that red-green-refactor is meaningful. If you are in a command shell that supports colors, passing tests will be green while failing tests will be red.

Run Code Coverage to see how well your test cases exercise your code:

$ coverage run test_server.py
$ coverage report -m --include=server.py

This is particularly useful because it reports the line numbers for the code that is not covered so that you can write more test cases.

You can even run nosetests with coverage

$ nosetests --with-coverage --cover-package=server

Try and get as close to 100% coverage as you can.

When you are done, you can exit and shut down the vm with:

$ exit
$ vagrant halt

If the VM is no longer needed you can remove it with:

$ vagrant destroy

* server.py -- the main Service using Python Flask
* test_server.py -- test cases using unittest
* ./spec/test_server_spec.py -- test specs using noseOfYeti

This repo is part of the DevOps course at NYU.