Everyday Scripting with Ruby: For Teams, Testers, and You

297 Pages·2007·2.016 MB·English

by  Brian Marick

What readers are saying about
Everyday Scripting with Ruby
What a wondrous collection of recipes, guidelines, warnings, compre-
hensive examples, metaphors, exercises, and questions! It’s a terrific
value to softwaretesting practitioners who want to get the most from
their test automation effort.
Grigori Melnik
Lecturer, University of Calgary
A fantastictype-along-with-me introduction to a powerful scripting
language that starts in the shallows and then moves into the depths
turning the reader into an accomplished Ruby scripter, almost with-
out them noticing it!
Erik Petersen
Emprove
Finally a hands-on book that is filled with gems of wisdom for the test-
ing community. By following the book’s easy-to-read chapters, real-life
code samples, and superb coverage of complex topics like test-driven
design and inheritance, a tester will not only take her testing career to
the next level but also contribute immensely to the software develop-
ment at her organization.
Gunjan Doshi
VP of Product Development and Process Excellence,
Community Connect, Inc
Marick explains the Ruby language using a series of short, practical
examples. Watir users and other testers who want to learn Ruby will
find it very accessible.
Bret Pettichord
Lead Developer, Watir
When you’ve read this book, you will be able to automate software
tests, which will give you an edge on most of your QA workmates. You
will be able to program in Ruby, which is a joy in itself. You will have
created several very useful utilities and will know how to adapt them
to meet your particular needs. All of the above will have been achieved
briskly and pleasantly. You will become a more effective tester and,
most likely, will have a fine time in the process.
George Hawthorne
Consultant, Oblomov Consulting
The book is an excellent read, is very informative, and covers a lot of
ground in a relatively slim book. I think this is always a good idea.
I have a lot of 800+ page tech books that I’ve read about the first
half or two thirdsof, because they are padded toward the end with
very esoteric information. This book held my interest throughout—I
have a full-time job and a ten-month-old son and still managed to get
through these examples in around a week! Brian’s personality comes
through (e.g., the Kennel containing Barkers) in a good way that helps
rather than hinders in understanding the material.
Paddy Healey
Enterprise Systems Engineer, Aventail Corporation
The chapters, examples, and exercises on regular expressions are
worth the cost of the book alone! Everythingelse is more than just
gravy—it’s every kind of dessert you didn’t know you could have.
Whether you are just beginning to script or have been scripting for
several years, this book will be an invaluable resource. The examples
and exercises, Ruby facts, step-by-step approach, and explanations
will help you kick up your automation efforts to a whole new level!
Paul Carvalho
Consultant, SoftwareTesting and Quality Services

Everyday Scripting with Ruby
For Teams, Testers, and You
Brian Marick
The Pragmatic Bookshelf
Raleigh,NorthCarolina Dallas,Texas
Many of the designations used by manufacturers and sellers to distinguish their prod-
uctsareclaimedastrademarks.Wherethosedesignationsappearinthisbook,andThe
Pragmatic Programmers, LLC was aware of a trademark claim, the designations have
been printed in initial capital letters or in all capitals. The Pragmatic Starter Kit, The
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devicearetrademarksofThePragmaticProgrammers,LLC.
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assumesnoresponsibility for errorsor omissions,or for damagesthatmay result from
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Our Pragmatic courses, workshops, and other products can help you and your team
create better software and have more fun. For more information, as well as the latest
Pragmatictitles,pleasevisitusat
http://www.pragmaticprogrammer.com
Copyright©2006BrianMarick.
Allrightsreserved.
Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmit-
ted, in any form, or by any means, electronic,mechanical,photocopying, recording, or
otherwise,withoutthepriorconsentofthepublisher.
PrintedintheUnitedStatesofAmerica.
ISBN-10:0-9776166-1-4
ISBN-13:978-0-9776166-1-9
Printedonacid-freepaperwith85%recycled,30%post-consumercontent.
Firstprinting,December2006
Version:2007-1-25
ToDawn,myBestBeloved,bestfriend,androlemodel
Andtoshoemakers’childreneverywhere
Contents
1 Introduction 13
1.1 How the Book Works . . . . . . . . . . . . . . . . . . . . . 15
1.2 An Outline of the Book . . . . . . . . . . . . . . . . . . . 16
1.3 Service After the Sale . . . . . . . . . . . . . . . . . . . . 17
1.4 Supplements . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.5 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 18
2 Getting Started 19
2.1 Download the Practice Files. . . . . . . . . . . . . . . . . 19
2.2 In the Beginning Was the Command Line. . . . . . . . . 20
2.3 Do You Need to Install Ruby? . . . . . . . . . . . . . . . . 22
2.4 Installing Ruby . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5 Your Two Basic Tools . . . . . . . . . . . . . . . . . . . . 23
2.6 Prompts, Command Lines, Prompts, and irb . . . . . . . 24
2.7 It’s Time to Make Mistakes . . . . . . . . . . . . . . . . . 26
I The Basics 29
3 A First Script: Comparing File Inventories 30
3.1 A Script in Action. . . . . . . . . . . . . . . . . . . . . . . 30
3.2 The Ruby Universe . . . . . . . . . . . . . . . . . . . . . . 31
3.3 Objects Send and Receive Messages . . . . . . . . . . . . 31
3.4 Variables Name Objects . . . . . . . . . . . . . . . . . . . 33
3.5 Comparing Arrays . . . . . . . . . . . . . . . . . . . . . . 34
3.6 Printing to the Screen . . . . . . . . . . . . . . . . . . . . 35
3.7 Making a Script. . . . . . . . . . . . . . . . . . . . . . . . 36
3.8 Where Do We Stand? . . . . . . . . . . . . . . . . . . . . 38
3.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
CONTENTS 9
4 Ruby Facts: Arrays 39
5 Three Improvements and a Bug Fix 43
5.1 Command-line Arguments . . . . . . . . . . . . . . . . . 43
5.2 Ignoring Case . . . . . . . . . . . . . . . . . . . . . . . . . 45
5.3 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
5.4 Dissecting Strings . . . . . . . . . . . . . . . . . . . . . . 51
5.5 Fixing a Bug . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.6 Where Do We Stand? . . . . . . . . . . . . . . . . . . . . 55
5.7 Prelude to the Exercises . . . . . . . . . . . . . . . . . . . 56
5.8 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
6 Ruby Facts: If, Equality Testing, and Unless 61
6.1 if ...elsif ...else . . . . . . . . . . . . . . . . . . . . . . . 61
6.2 When Are Objects Equal? . . . . . . . . . . . . . . . . . . 63
6.3 A Shorthand Version of if . . . . . . . . . . . . . . . . . . 63
6.4 unless . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
6.5 The Question Mark Operator . . . . . . . . . . . . . . . . 64
II Growing a Script 66
7 The Churn Project: Writing Scripts without Fuss 67
7.1 The Project . . . . . . . . . . . . . . . . . . . . . . . . . . 67
7.2 Building a Solution . . . . . . . . . . . . . . . . . . . . . 69
7.3 Where Do We Stand? . . . . . . . . . . . . . . . . . . . . 91
7.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
8 Ruby Facts: Booleans 94
8.1 Other Boolean Operators . . . . . . . . . . . . . . . . . . 94
8.2 Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . 94
8.3 Every Object Is a Truth Value . . . . . . . . . . . . . . . 96
8.4 Boolean Expressions Can Select Objects . . . . . . . . . 96
9 Our Friend, the Regular Expression 98
9.1 Regular Expressions Match Strings . . . . . . . . . . . . 99
9.2 Dissecting Stringswith Regular Expressions . . . . . . . 101
9.3 Reordering an Array . . . . . . . . . . . . . . . . . . . . . 102
9.4 Where Do We Stand? . . . . . . . . . . . . . . . . . . . . 104
9.5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
CONTENTS 10
10 Ruby Facts: Regular Expressions 106
10.1 Special Characters . . . . . . . . . . . . . . . . . . . . . . 106
10.2 Grouping and Alternatives . . . . . . . . . . . . . . . . . 108
10.3 Taking StringsApart . . . . . . . . . . . . . . . . . . . . . 108
10.4 Variables Behind the Scenes . . . . . . . . . . . . . . . . 109
10.5 Regular Expression Options . . . . . . . . . . . . . . . . 109
10.6 Wait, There’s More... . . . . . . . . . . . . . . . . . . . . 110
10.7 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
11 Classes Bundle Data and Methods 112
11.1 Classes Define Methods . . . . . . . . . . . . . . . . . . . 115
11.2 Objects Contain Data . . . . . . . . . . . . . . . . . . . . 116
11.3 Where Do We Stand? . . . . . . . . . . . . . . . . . . . . 120
11.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
12 Ruby Facts: Classes (with a Side Order of Symbols) 126
12.1 Defining Accessors . . . . . . . . . . . . . . . . . . . . . . 126
12.2 Self . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
12.3 Class Methods . . . . . . . . . . . . . . . . . . . . . . . . 133
12.4 Class Variables and Globals . . . . . . . . . . . . . . . . 136
12.5 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
III Working in a World Full of People 138
13 Scraping Web Pages with Regular Expressions 139
13.1 Treating Web Pages Like Files . . . . . . . . . . . . . . . 140
13.2 Restricting Attention to Part of the Page . . . . . . . . . 142
13.3 Plucking Out the Title and Authors . . . . . . . . . . . . 144
13.4 Hashes StoreNamed Data . . . . . . . . . . . . . . . . . 146
13.5 Taking the Trip . . . . . . . . . . . . . . . . . . . . . . . . 147
13.6 Exercise Yourself . . . . . . . . . . . . . . . . . . . . . . . 149
14 Other Ways of Working with Web Applications 152
14.1 Handling XHTML . . . . . . . . . . . . . . . . . . . . . . . 152
14.2 Driving the Browser . . . . . . . . . . . . . . . . . . . . . 154
14.3 Direct Access to Underlying Protocols . . . . . . . . . . . 155