RSpec Essentials: Develop testable, modular, and maintainable Ruby software for the real world using RSpec

223 Pages·2016·4.789 MB·English

by  Mani Tadayon

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RSpec Essentials
Develop testable, modular, and maintainable
Ruby software for the real world using RSpec
Mani Tadayon
BIRMINGHAM - MUMBAI
www.it-ebooks.info
RSpec Essentials
Copyright © 2016 Packt Publishing
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First published: April 2016
Production reference: 1130416
Published by Packt Publishing Ltd.
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Birmingham B3 2PB, UK.
ISBN 978-1-78439-590-2
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Credits
Author Project Coordinator
Mani Tadayon Judie Jose
Reviewers Proofreader
Stefan Daschek Safis Editing
Nola Stowe
Indexer
Rekha Nair
Commissioning Editor
Amarabha Banerjee
Graphics
Abhinash Sahu
Acquisition Editor
Reshma Raman
Production Coordinator
Manu Joseph
Content Development Editor
Rashmi Suvarna
Cover Work
Manu Joseph
Technical Editor
Anushree Arun Tendulkar
Copy Editor
Safis Editing
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About the Author
Mani Tadayon first learned to program as a shy 7th grader on an Apple IIe using
BASIC. He went on to learn Pascal, C++, Java, JavaScript, Visual Basic, and PHP
before becoming a Ruby developer in 2008. With 15 years of experience in the software
industry, he has developed expertise in web development, infrastructure, and testing.
Mani's interests and education are broad, with degrees in foreign languages, computer
science, and geography. He lives just far enough from Silicon Valley with his family
and their many, many Shiba Inus.
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About the Reviewers
Stefan Daschek started hacking on computers back in the days of the Commodore
64/128. Since then, he has studied computer sciences at TU Vienna and founded
his own company, Büro DIE ANTWORT. Currently, he is mainly developing and
maintaining complex web applications written in Ruby on Rails, and sometimes
soldering stuff and building small robots. His original Commodore 128 is still
working and used for a collective session of Summer Games every so often.
Nola Stowe has been programming with Ruby since Rails 0.8 and testing with RSpec
since its early days. She is an independent consultant, helping to augment teams of
Ruby and Clojure developers. She has also been a technical reviewer for Instant RSpec
Test-Driven Development, Packt Publishing and The Rails Way, First Edition. Nola blogs
at http://blog.rubygeek.com and http://www.clojuregeek.com.
Thanks to my husband Nick for doing the mundane things in life to
allow me time do what I love doing. You are the greatest!
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Table of Contents
Preface v
Chapter 1: Exploring Testability from Unit Tests to
Behavior-Driven Development 1
The promise of testing 1
Testability 3
Technical assumptions 4
Running our first spec 5
Understanding the unit test 9
Writing specs with RSpec 12
Test-driven development 14
Behavior-driven development 15
Summary 16
Chapter 2: Specifying Behavior with Examples and Matchers 17
Structure of a spec file 17
Using let and context 20
Matchers 23
Built-in matchers 23
Custom matchers 24
Enhanced context in matcher output 26
Creating a good custom error message 29
Improving application code 31
Testing for errors 35
Summary 40
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Table of Contents
Chapter 3: Taking Control of State with Doubles and Hooks 41
Why mock? 41
Mocks, stubs, and doubles 45
Using hooks 46
Controlling when hooks are executed 52
Advanced state control with hooks and mocks 53
Summary 58
Chapter 4: Setting Up and Cleaning Up 59
Configuring RSpec with spec_helper.rb 59
Initialization and configuration of resources 62
A case study of test simplicity with an external service 63
A case study of production faithfulness with a test resource instance 76
Summary 83
Chapter 5: Simulating External Services 85
The importance of external web services 85
Mock HTTP responses with custom helpers 86
Using real-world requests for mock responses 87
Using WebMock for mock HTTP requests 93
Using VCR for mock requests 94
Summary 98
Chapter 6: Driving a Web Browser with Capybara 99
Getting started with Capybara and Selenium 100
Integrating Capybara with RSpec 103
Why Capybara? 106
Black-box JavaScript tests with a real browser 107
Summary 108
Chapter 7: Building an App from the Outside In with
Behavior-Driven Development 109
Exploring BDD 110
MMFs by example 111
Using TodoMVC 113
Specifying the MMF 114
Configuring RSpec to run a feature file 116
The BDD process begins 119
Building web apps with Rack 120
Serving static files using Rack middleware 123
Summary 125
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Table of Contents
Chapter 8: Tackling the Challenges of End-to-end Testing 127
Step 1 – building the view 127
Step 2 – defining the API 133
Step 3 – finishing the view 157
The pros and cons of BDD 160
Simple Rack authentication middleware 161
JSON Web Token 164
Summary 166
Chapter 9: Configurability 167
Configuration and testability 168
What is so important about configuration? 168
What does all this have to do with testing? 169
File-based configuration management 169
A better configuration manager 173
Summary 184
Chapter 10: Odds and Ends 185
Reducing duplication with shared example groups 185
Mocking time 193
Detecting false negatives and false positives 196
Testing mixins with dummy containers 200
Summary 202
Index 203
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