Testing Python E-Book

David Sale

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 286

Veröffentlichungsjahr: 2014

Beschreibung

Fundamental testing methodologies applied to the popular Python language Testing Python; Applying Unit Testing, TDD, BDD and Acceptance Testing is the most comprehensive book available on testing for one of the top software programming languages in the world. Python is a natural choice for new and experienced developers, and this hands-on resource is a much needed guide to enterprise-level testing development methodologies. The book will show you why Unit Testing and TDD can lead to cleaner, more flexible programs. Unit Testing and Test-Driven Development (TDD) are increasingly must-have skills for software developers, no matter what language they work in. In enterprise settings, it's critical for developers to ensure they always have working code, and that's what makes testing methodologies so attractive. This book will teach you the most widely used testing strategies and will introduce to you to still others, covering performance testing, continuous testing, and more. * Learn Unit Testing and TDD--important development methodologies that lie at the heart of Agile development * Enhance your ability to work with Python to develop powerful, flexible applications with clean code * Draw on the expertise of author David Sale, a leading UK developer and tech commentator * Get ahead of the crowd by mastering the underappreciated world of Python testing Knowledge of software testing in Python could set you apart from Python developers using outmoded methodologies. Python is a natural fit for TDD and Testing Python is a must-read text for anyone who wants to develop expertise in Python programming.

Leseprobe

This edition first published 2014

© 2014 David Sale

Registered office

John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, United Kingdom

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Trademarks: Wiley and the Wiley logo are trademarks or registered trademarks of John Wiley & Sons, Inc. and/or its affiliates in the United States and/or other countries, and may not be used without written permission. Python is a registered trademark of the Python Software Foundation. All other trademarks are the property of their respective owners. John Wiley & Sons, Ltd. is not associated with any product or vendor mentioned in the book.

A catalogue record for this book is available from the British Library.

ISBN 978-1-118-90122-9 (paperback); ISBN 978-1-118-90124-3 (ePub); 978-1-118-90125-0 (ePDF)

Set in 10/12.5 ChaparralPro-Light by TCS/SPS

Printed in the USA by Bind-Rite

Publisher’s Acknowledgements

Some of the people who helped bring this book to market include the following:

Editorial and Production

VP Consumer and Technology Publishing Director: Michelle Leete

Associate Director–Book Content Management: Martin Tribe

Associate Publisher: Chris Webb

Executive Commissioning Editor: Craig Smith

Project Editor: Sydney Argenta

Copy Editor: Debbye Butler

Technical Editors: Jeff Yonker, Alex Bradbury, Andrew Robinson, and Harry Percival

Editorial Manager: Rev Mengle

Senior Project Editor: Sara Shlaer

Editorial Assistant: Claire Johnson

Marketing

Marketing Manager: Lorna Mein

Assistant Marketing Manager: Dave Allen

About the Author

DAVID SALE is a Software Developer currently working at British Sky Broadcasting (BSkyB) in London, UK as of 2014. He obtained a degree in Computing at the University of Leeds. Whilst studying Computing, Python was taught as the main programming language of the course. This is very different to many other University’s where languages such as Java are taught initially.

This is where David’s interest in Python first began and he has looked to further his knowledge in what has become his core programming language.

Following University, David joined BSkyB in September 2011, as part of the Software Engineering Academy graduate scheme. The scheme proved to be an excellent platform for David to launch his career in software development.

Notably, David has worked on a RESTful Python application that models BSkyB’s products and offers, applies complex pricing rules and business logic, whilst delivering a completely data driven approach to the problem. David has also worked on a project using a Hypermedia approach to sharing data across the application stack to deliver an innovative solution delivering sales to existing customers of BSkyB.

David quickly began making his presence known in the Python Community, having written web articles on various Python topics. David has also given talks on Behaviour Driven Development and Agile Development at the EuroPython conference, which was held in Florence, Italy in 2012 and 2013 respectively, with videos of the talks available on YouTube.

David follows Agile Development principles whilst working at BSkyB, with pair programming and Test/Behaviour Driven Development a must. From this focus on testing from such an early point in his career, he has picked up many tips and techniques in Python testing which allows development of quality software, which the business has up most confidence in. It is hoped the tips and advice in this book allow you to learn and improve your daily testing skills in Python.

You can find more on David’s current and previous projects at: www.dsale.co.uk.

Acknowledgments

First and foremost I would like to thank Craig Smith, Executive Commissioning Editor at Wiley for approaching me with the opportunity to write this book and giving me the confidence in my writing to go for this project; Sydney Jones Argenta, Project Editor, for editing the book so diligently and keeping me up to date throughout the project; Jeff Younker, Alex Bradbury, Andrew Robinson, and Harry Percival Technical Editors for ensuring my code was up to the standard expected by the community and the best it could be.

Secondly, I’d like to give my gratitude to my employer British Sky Broadcasting (Sky). I joined Sky through their Software Engineering Academy graduate scheme and have since progressed to a Software Developer. Without their investment in me, I would not have learned some of the skills and advice that I can now share in this book. They also happily granted me permission to work on this book and helped me find the time to deliver the project alongside my work commitments. Please visit http://workforsky.com if you are interested in joining the team or www.skygraduates.com for more on graduate schemes at Sky.

I’d like to thank my partner Katherine Sweeney, for being so patient in supporting me whilst working on this book. Without her love and support, I would never have dreamed to deliver a project like this and she constantly reminds me to believe in myself. This book is an achievement for us together and I am thankful to have her by my side.

Finally, I would like to thank my brothers Stefan and Matthew Sale for always supporting me in my endeavours but in particular my parents, Ronald and Jennifer Sale. From an early age I have always been taught to work hard and reach for your goals. This book is testament to those words and without the drive to achieve that they have passed on to me; I could never have seen such a big project through. This book is for them and all the people who have supported me in my career as a Software Developer.

Testing Python®

Table of Contents

Introduction

Chapter 1: A History of Testing

You Do Test, Don’t You?

Fundamentals and Best Practices

Python Installation

Pip

Virtualenv

Source Control (SVN, Git)

Interactive Development Environment (IDE)

Summary

Chapter 2: Writing Unit Tests

What Is Unit Testing?

What Should You Test?

Writing Your First Unit Test

Checking Values with the assertEquals Method

Checking Exception Handling with assertRaises

Following the PEP-8 Standard

Unit Test Structure

Additional Unit Test Examples

Getting Clever with assertRaises

Making Your Life Easier with setUp

Useful Methods in Unit Testing

Summary

Chapter 3: Utilizing Unit Test Tools

Using Python’s Nose

Installing Nose

Using Nose’s Best Features

PyTest: An Alternative Test Runner

Installing PyTest

PyTest’s Best Features

Choosing Between Nose and PyTest

Mock and Patch Tricky Situations

Installing the Mock Library

Mocking a Class and Method Response

When Mock Won’t Do, Patch!

Summary

Chapter 4: Writing Testable Documentation

Writing Your First Doctest

The Python Shell

Adding Doctests to a Method

Running Your Doctests

Handling Error Cases

Advanced Doctest Usage

Improving Doctests with Nose Integration

Summary

Resources

Chapter 5: Driving Your Development with Tests

Agile Development

Adopting the Agile Process Now

Ethos of Test Driven Development

Advantages of Test Driven Development

Ping-Pong Programming

Test Driving Your Problem

Writing Your Failing Test

Making Your Test Pass

Driving More Features with Tests

Wrapping Up the Task

Summary

Resources

Chapter 6: Writing Acceptance Tests

What Is Acceptance Testing?

Anatomy of an Acceptance Test

Using Gherkin Syntax

The Magic Is in the Step File

Goals of Acceptance Testing

Implementing Developer and QA Collaboration

Letting Behavior Drive Your Problem

Writing Your Failing Acceptance Test

Defining Your Steps

Implementing Your Code

Developing More of the Feature

Delivering the Finished Article

Advanced Acceptance Test Techniques

Scenario Outline

Tables of Data in Scenarios

Summary

Resources

Chapter 7: Utilizing Acceptance Test Tools

Cucumber: The Acceptance Test Standard

Lettuce in Detail

Tagging

Fail Fast

Nosetest Integration

Robot: An Alternative Test Framework

Installing Robot

Writing a Test Case

Implementing Keywords

Running Robot Tests

Summary

Resources

Chapter 8: Maximizing Your Code’s Performance

Understanding the Importance of Performance Testing

JMeter and Python

Installation

Configuring Your Test Plans

Utilizing Your Test Plans Effectively

Code Profiling with cProfile

Run a cProfile Session

Analyzing the cProfile Output

Summary

Resources

Chapter 9: Looking After Your Lint

Coming to Grips with Pylint

Installing Pylint

Using Pylint

Understanding the Pylint Report

Customizing Pylint’s Output

Covering All Your Code with Unit Tests

Installing Coverage

Using Coverage

Advanced Coverage Options

Summary

Resources

Chapter 10: Automating Your Processes

Build Paver Tasks

Installing Paver

Creating a Paver Task

Executing Paver Tasks

Defining a Default Build

Setting Up Automated Builds

Installing Jenkins

Adding Coverage and PyLint Reports

Making Your Build Status Highly Visible

Summary

Resources

Chapter 11: Deploying Your Application

Deploying Your Application to Production

Creating a Deployable Artifact

QA Environment

Implementing Stage and Production Environments

Implementing a Cloud Deployment

Smoke Testing a Deployed Application

Example Application Stack

Smoke Test Scenarios

Implementing Smoke Tests

Summary

Resources

Chapter 12: The Future of Testing Python

Stub the Solution

Making Deployment Natural

Automating (Nearly) Everything

Working in Public

Collaborating on Step Definitions

Final Thoughts

Resources

Guide

Table of Contents

Begin Reading

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Introduction

IF YOU HAVE picked up this book, you clearly have some interest in the world of Python. Perhaps you have just started to learn the language. Maybe you have some Python experience and are looking to learn more about the world of testing. You also could have many years of Python under your belt and want to refresh your testing skills. Whatever your reasons, you will pick up some new skills.