Programming Language Preference
Test Automation for Web Applications¶
Many, perhaps most, software applications today are written as web-based applications to be run in an Internet browser. The effectiveness of testing these applications varies widely among companies and organizations. In an era of highly interactive and responsive software processes where many organizations are using some form of Agile methodology, test automation is frequently becoming a requirement for software projects. Test automation is often the answer. Test automation means using a software tool to run repeatable tests against the application to be tested. For regression testing this provides that responsiveness.
There are many advantages to test automation. Most are related to the repeatability of the tests and the speed at which the tests can be executed. There are a number of commercial and open source tools available for assisting with the development of test automation. Selenium is possibly the most widely-used open source solution. This user’s guide will assist both new and experienced Selenium users in learning effective techniques in building test automation for web applications.
This user’s guide introduces Selenium, teaches its features, and presents commonly used best practices accumulated from the Selenium community. Many examples are provided. Also, technical information on the internal structure of Selenium and recommended uses of Selenium are provided.
Test automation has specific advantages for improving the long-term efficiency of a software team’s testing processes. Test automation supports:
- Frequent regression testing
- Rapid feedback to developers
- Virtually unlimited iterations of test case execution
- Support for Agile and extreme development methodologies
- Disciplined documentation of test cases
- Customized defect reporting
- Finding defects missed by manual testing
To Automate or Not to Automate?¶
Is automation always advantageous? When should one decide to automate test cases?
It is not always advantageous to automate test cases. There are times when manual testing may be more appropriate. For instance, if the application’s user interface will change considerably in the near future, then any automation might need to be rewritten anyway. Also, sometimes there simply is not enough time to build test automation. For the short term, manual testing may be more effective. If an application has a very tight deadline, there is currently no test automation available, and it’s imperative that the testing get done within that time frame, then manual testing is the best solution.
Selenium is a set of different software tools each with a different approach to supporting test automation. Most Selenium QA Engineers focus on the one or two tools that most meet the needs of their project, however learning all the tools will give you many different options for approaching different test automation problems. The entire suite of tools results in a rich set of testing functions specifically geared to the needs of testing of web applications of all types. These operations are highly flexible, allowing many options for locating UI elements and comparing expected test results against actual application behavior. One of Selenium’s key features is the support for executing one’s tests on multiple browser platforms.
Brief History of The Selenium Project¶
Jump to 2008. The Beijing Olympics mark China’s arrival as a global power, massive mortgage default in the United States triggers the worst international recession since the Great Depression, The Dark Knight is viewed by every human (twice), still reeling from the untimely loss of Heath Ledger. But the most important story of that year was the merging of Selenium and WebDriver. Selenium had massive community and commercial support, but WebDriver was clearly the tool of the future. The joining of the two tools provided a common set of features for all users and brought some of the brightest minds in test automation under one roof. Perhaps the best explanation for why WebDriver and Selenium are merging was detailed by Simon Stewart, the creator of WebDriver, in a joint email to the WebDriver and Selenium community on August 6, 2009.
“Why are the projects merging? Partly because webdriver addresses some shortcomings in selenium (by being able to bypass the JS sandbox, for example. And we’ve got a gorgeous API), partly because selenium addresses some shortcomings in webdriver (such as supporting a broader range of browsers) and partly because the main selenium contributors and I felt that it was the best way to offer users the best possible framework.”
Selenium’s Tool Suite¶
Selenium is composed of multiple software tools. Each has a specific role.
Selenium 2 (aka. Selenium Webdriver)¶
Selenium 2 is the future direction of the project and the newest addition to the Selenium toolkit. This brand new automation tool provides all sorts of awesome features, including a more cohesive and object oriented API as well as an answer to the limitations of the old implementation.
As you can read in Brief History of The Selenium Project, both the Selenium and WebDriver developers agreed that both tools have advantages and that merging the two projects would make a much more robust automation tool.
Selenium 2.0 is the product of that effort. It supports the WebDriver API and underlying technology, along with the Selenium 1 technology underneath the WebDriver API for maximum flexibility in porting your tests. In addition, Selenium 2 still runs Selenium 1’s Selenium RC interface for backwards compatibility.
Selenium 1 (aka. Selenium RC or Remote Control)¶
As you can read in Brief History of The Selenium Project, Selenium RC was the main Selenium project for a long time, before the WebDriver/Selenium merge brought up Selenium 2, the newest and more powerful tool.
Selenium IDE (Integrated Development Environment) is a prototyping tool for building test scripts. It is a Firefox plugin and provides an easy-to-use interface for developing automated tests. Selenium IDE has a recording feature, which records user actions as they are performed and then exports them as a reusable script in one of many programming languages that can be later executed.
Even though Selenium IDE has a “Save” feature that allows users to keep the tests in a table-based format for later import and execution, it is not designed to run your test passes nor is it designed to build all the automated tests you will need. Specifically, Selenium IDE doesn’t provide iteration or conditional statements for test scripts. At the time of writing there is no plan to add such thing. The reasons are partly technical and partly based on the Selenium developers encouraging best practices in test automation which always requires some amount of programming. Selenium IDE is simply intended as a rapid prototyping tool. The Selenium developers recommend for serious, robust test automation either Selenium 2 or Selenium 1 to be used with one of the many supported programming languages.
Selenium-Grid allows the Selenium RC solution to scale for large test suites and for test suites that must be run in multiple environments. Selenium Grid allows you to run your tests in parallel, that is, different tests can be run at the same time on different remote machines. This has two advantages. First, if you have a large test suite, or a slow-running test suite, you can boost its performance substantially by using Selenium Grid to divide your test suite to run different tests at the same time using those different machines. Also, if you must run your test suite on multiple environments you can have different remote machines supporting and running your tests in them at the same time. In each case Selenium Grid greatly improves the time it takes to run your suite by making use of parallel processing.
Choosing Your Selenium Tool¶
Many people get started with Selenium IDE. If you are not already experienced with a programming or scripting language you can use Selenium IDE to get familiar with Selenium commands. Using the IDE you can create simple tests quickly, sometimes within seconds.
We don’t, however, recommend you do all your test automation using Selenium IDE. To effectively use Selenium you will need to build and run your tests using either Selenium 2 or Selenium 1 in conjunction with one of the supported programming languages. Which one you choose depends on you.
At the time of writing the Selenium developers are planning on the Selenium-WebDriver API being the future direction for Selenium. Selenium 1 is provided for backwards compatibility. Still, both have strengths and weaknesses which are discussed in the corresponding chapters of this document.
We recommend those who are completely new to Selenium to read through these sections. However, for those who are adopting Selenium for the first time, and therefore building a new test suite from scratch, you will probably want to go with Selenium 2 since this is the portion of Selenium that will continue to be supported in the future.
Supported Browsers and Platforms¶
In Selenium 2.0, the supported browsers vary depending on whether you are using Selenium-WebDriver or Selenium-RC.
Selenium-WebDriver supports the following browsers along with the operating systems these browsers are compatible with.
- Google Chrome
- Internet Explorer 6, 7, 8, 9, 10 - 32 and 64-bit where applicable
- Firefox: latest ESR, previous ESR, current release, one previous release
- Android (with Selendroid or appium)
- iOS (with ios-driver or appium)
Selenium 1.0 and Selenium-RC.¶
This is the old, support platform for Selenium 1.0. It should still apply to the Selenium 2.0 release of Selenium-RC.
|Browser||Selenium IDE||Selenium 1 (RC)||Operating Systems|
|Firefox 3.x||Record and playback tests||Start browser, run tests||Windows, Linux, Mac|
|Firefox 3||Record and playback tests||Start browser, run tests||Windows, Linux, Mac|
|Firefox 2||Record and playback tests||Start browser, run tests||Windows, Linux, Mac|
|IE 8||Test execution only via Selenium RC*||Start browser, run tests||Windows|
|IE 7||Test execution only via Selenium RC*||Start browser, run tests||Windows|
|IE 6||Test execution only via Selenium RC*||Start browser, run tests||Windows|
|Safari 4||Test execution only via Selenium RC||Start browser, run tests||Windows, Mac|
|Safari 3||Test execution only via Selenium RC||Start browser, run tests||Windows, Mac|
|Safari 2||Test execution only via Selenium RC||Start browser, run tests||Windows, Mac|
|Opera 10||Test execution only via Selenium RC||Start browser, run tests||Windows, Linux, Mac|
|Opera 9||Test execution only via Selenium RC||Start browser, run tests||Windows, Linux, Mac|
|Opera 8||Test execution only via Selenium RC||Start browser, run tests||Windows, Linux, Mac|
|Google Chrome||Test execution only via Selenium RC||Start browser, run tests||Windows, Linux, Mac|
|Others||Test execution only via Selenium RC||Partial support possible**||As applicable|
* Tests developed on Firefox via Selenium IDE can be executed on any other supported browser via a simple Selenium RC command line.
** Selenium RC server can start any executable, but depending on browser security settings there may be technical limitations that would limit certain features.
Flexibility and Extensibility¶
You’ll find that Selenium is highly flexible. There are many ways you can add functionality to both Selenium test scripts and Selenium’s framework to customize your test automation. This is perhaps Selenium’s greatest strength when compared with other automation tools. These customizations are described in various places throughout this document. In addition, since Selenium is Open Source, the sourcecode can always be downloaded and modified.
What’s in this Book?¶
This user’s guide targets both new users and those who have already used Selenium but are seeking additional knowledge. We introduce Selenium to new users and we do not assume prior Selenium experience. We do assume, however, that the user has at least a basic understanding of test automation. For the more experienced user, this guide can act as a reference. For the more experienced, we recommend browsing the chapter and subheadings. We’ve provided information on the Selenium architecture, examples of common usage, and a chapter on test design techniques.
The remaining chapters of the reference present:
- Selenium IDE
- Introduces Selenium IDE and describes how to use it to build test scripts. using the Selenium Integrated Development Environment. If you are not experienced in programming, but still hoping to learn test automation this is where you should start and you’ll find you can create quite a few automated tests with Selenium IDE. Also, if you are experienced in programming, this chapter may still interest you in that you can use Selenium IDE to do rapid prototyping of your tests. This section also demonstrates how your test script can be “exported” to a programming language for adding more advanced capabilities not supported by Selenium IDE.
- Selenium 2
- Explains how to develop an automated test program using Selenium 2.
- Selenium 1
- Explains how to develop an automated test program using the Selenium RC API. Many examples are presented in both programming languages and scripting languages. Also, the installation and setup of Selenium RC is covered here. The various modes, or configurations, that Selenium RC supports are described, along with their trade-offs and limitations. An architecture diagram is provided to help illustrate these points. Solutions to common problems frequently difficult for new Sel-R users are described here, for instance, handling Security Certificates, https requests, pop-ups, and the opening of new windows.
- Test Design Considerations
- This chapter presents programming techniques for use with Selenium-WebDriver and Selenium RC. We also demonstrate techniques commonly asked about in the user forum such as how to design setup and teardown functions, how to implement data-driven tests (tests where one can vary the data between test passes) and other methods of programming common test automation tasks.
- This chapter is not yet developed.
- User extensions
- Describes ways that Selenium can be modified, extended and customized.