Using The Page Object Pattern

Using the Page Object Pattern to Improve Functional Test Maintainability Dante Briones Principal Consultant Electronic Ingenuity LLC http://electronicingenuity.com Friday, 07 August, 2009

The Page Object Pattern • Technique for structuring test code that: • Promotes reuse and reduces duplication • Makes tests readable • Makes tests more robust (less brittle) • Improves maintainability, particularly if the application is rapidly evolving Friday, 07 August, 2009

The Page Object Pattern • Demos will be coded in Java • Everything we discuss is applicable to other strongly-typed languages (e.g. C#) • Most things are applicable to dynamically- typed languages (e.g. Ruby, Python, Perl) Friday, 07 August, 2009

Selenium IDE Quick Poll • How many using Se IDE? • How many create tests primarily through record & playback? Friday, 07 August, 2009

Selenium IDE It’s Great Because: • It’s Free • It’s Free • Requires little or no programming experience Friday, 07 August, 2009

Selenium IDE It falls short because: • Selenese is not a programming language • No support for loops/iteration • No support for conditionals (if...else) • No way to eliminate duplicated code! Friday, 07 August, 2009

Selenium IDE Why is duplication bad? • Has this ever happened to you? • A tiny change to the app causes several test failures? • Let’s see an example Friday, 07 August, 2009

Demo Friday, 07 August, 2009

Selenium IDE Why is duplication bad? • Fixing the tests will require more work than the change that caused the failure • Duplication makes code less maintainable Friday, 07 August, 2009

Selenium IDE Summary • Great productivity for the ﬁrst few tests • Maintainability decreases as the test suite grows • How can we do better? Friday, 07 August, 2009

Start Coding Your Tests a.k.a. “Write tests in a programming language” Friday, 07 August, 2009

Coding Your Tests Quick Poll • How many are using Selenium RC? Friday, 07 August, 2009

Coding Your Tests How does this help? • We can eliminate duplication by building abstractions • Let’s see an example of this Friday, 07 August, 2009

Coding Your Tests What happens next? • All commonly used methods get pulled into the base class of all tests • As the test suite grows, so does the base class • Uh oh...the base class starts getting too big Friday, 07 August, 2009

Coding Your Tests How Big is Too Big? • You can’t tell someone else has already written the code you’re about to write • Frequent version control conﬂicts • Maintenance is an issue again Friday, 07 August, 2009

Coding Your Tests How to rein in your base class? • Observation: For any given page, most of the behavior does not apply • Example: you can’t change your password on the “view cart” page • What if we moved the page-speciﬁc behavior into a corresponding class? • Voila! The Page Object is born Friday, 07 August, 2009

The Page Object Friday, 07 August, 2009

The Page Object What does it do? • Consolidates the code for interacting with any given UI element • Allows you to model the UI in your tests Friday, 07 August, 2009

The Page Object What does it do? • Exposes methods that reﬂect the things a user can see and do on that page, e.g. • addItemToCart(), getPrice() • getEntryTitle(), saveDraft(), publishEntry() • Hides the details of telling the browser how to do those things Friday, 07 August, 2009

The Page Object Results • Test code is very readable • No duplication of Selenium API calls • Interactive documentation via Ctrl-Space • Eminently reusable code Friday, 07 August, 2009

The Page Object Results • This technique is framework-agnostic • Has been used with Selenium, WebDriver (Selenium 2.0), Watir, and others • I’ve even used it to drive desktop apps Friday, 07 August, 2009

The Page Object Results • Because it encapsulates the details of the test framework API: • You can use this technique to simplify the process of swapping frameworks • In theory, you only need to reimplement the Page base class. Friday, 07 August, 2009

But wait, there’s more! It gets better! • Page Objects improve maintainability • They also provide an opportunity to make test creation extremely quick (and maybe even fun!) • How? Page Objects + Method Chaining Friday, 07 August, 2009

Method Chaining What’s method chaining? • Change the signature of user behavior methods so that they return the page object itself • Allows multiple behavior methods to be called in sequence Friday, 07 August, 2009

Method Chaining What will it do for me? • Removes for “code clutter” • Tests become even more readable Friday, 07 August, 2009

Method Chaining How does it work in practice? • All Page Object methods return a reference to a Page Object • If the “user action” moves the focus to a different page, the method should return that page object • Otherwise, return the same page object • Time for an example Friday, 07 August, 2009

Method Chaining Results • Test code is even more readable • Very quick to write • (Actually kinda fun. Don’t tell anyone!) Friday, 07 August, 2009

Method Chaining Caveats • Dependent on tool support • Lots of options: IntelliJ IDEA, Eclipse, NetBeans, VisualStudio Friday, 07 August, 2009

Method Chaining Caveats • Tool support depends on language • Excellent support for strongly typed languages like Java and C# • Support is “up and coming” for dynamically typed languages (Ruby, Python, and Perl) Friday, 07 August, 2009

The Page Object Pattern • Technique for organizing test code that: • Promotes reuse and reduces duplication • Makes tests readable • Makes tests more robust (less brittle) • Improves maintainability, particularly if the application is rapidly evolving • Is just as quick record & playback! Friday, 07 August, 2009

Q &A Friday, 07 August, 2009

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Using The Page Object Pattern

by Dante Briones on Aug 07, 2009

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Using The Page Object Pattern — Presentation Transcript