What's the relation between Selenium WebDriver and these other tools?

Question

I've used Selenium IDE to test Drupal (PHP) sites but want to create more advanced tests with loops and such. I hear Selenium WebDriver is all the rage, but when I google it, all these terms pop up and make me confused:

Selenium 2 API
(Google) WebDriver
Selenium WebDriver
Selenium Grid
Selenese
PHPUnit
NGUnit
HtmlUnit
HttpUnit
JUnit
Sikuli Script
SimpleTest
Watir
soapUI
Groovy

I'm wondering about how all these fit together in the grand scheme of unit testing, and, more specifially, Selenium WebDriver. Like, what's the difference between them, which are comparable (do about the same thing), where do they overlap, what can x do that y can't,

1. Can I use all of them to test PHP sites?
2. Which could I (and should I) use in conjunction (and why) and
3. Would I need additional software to make that work (if so, what software),
4. When should I use what,
5. Is Selenese something I use instead of PHP when coding tests and if so, what's the advantage of that
6. Are there any other tools that I should use in conjunction with Selenium Webdriver?

Sorry if the question is too broad or to nooby (please critizise constructively and give me a chance to rephrase my question before handing out too many minus points---this is my first question in this forum). Of course I'm not expecting anyone to answer all of this, but please chip in if you think you can clear my confusion in any way. By the way, my programming skills are at an entry level so please keep that in mind when explaining.

Answer 1

"How to eat an elephant? One bite at a time." --- The scope of your question is so wide, that it is not possible to shows all subtle differences between different technologies you list. It would be more useful for you to focus on a single problem (e.g., interaction with Web browser) and then search for technology that helps you solve this problem. Therefore, I decided to center my answer around generic problems the listed technologies try to solve.

I posted my answer as community wiki, so others can improve it. Many of the technologies you listed I know only superficially, so I hope others will add more here.

Unit testing

Test framework enables execution of test cases automatically and reporting test results. Test framework usually provides a set of assertion predicates (e.g., isEqual) that will be used to compare actual system behavior with expected behavior (output) you define. Having tests cases with similar setup you may group them in test suites.

The family of frameworks for unit testing, i.e. testing of single components and functions, is known as xUnit. JUnit and NGUnit are implementations of such framework of Java language. phpUnit and SimpleTest would be for unit testing of PHP code pieces.

Interacting with external systems

During test execution, a test case implementation passes input data to the system under test and gets actual output data in return. Systems under tests cannot be called directly, when they expose different interfaces (e.g., SOAP). Hence, to speak to such a system, test case must use "glue", i.e., test driver that uses the protocol understood by the system. A test driver make easier for you to interact with such systems: prepare input data, parse output and make assertions on them.

• SOAPUI: Talking to Web services (exposing SOAP or RESTful interface), Web resources (HTTP interface), JMS queues, backend services for Flash/Flex applications (AMF interface).
• HTTPUnit, HTMLUnit: Interacting at low level with HTML Web sites and Web resources with HTTP interface
• Selenium WebDriver, Google WebDriver: Talking to Web browser (IE, FF, Chrome).

Integration and system testing

Some of those test drivers, like HTTPUnit and WebDrivers, can be used together with xUnit frameworks to automate completely testing process. Yes, xUnit frameworks were originally designed for unit testing, but currently are often used for launching integration and system tests.

Programming Languages

Groovy is a programming language for the Java VM. If you write APIs in Groovy, you might choose to test those APIs in Groovy too. You might also choose to test Java APIs in Groovy, but there are other JVM-based languages that you could use to test Java APIs as well.

To quote its Wikipedia page, "Sikuli is a visual technology to automate and test graphical user interfaces (GUI) using images (screenshots) of the software under test" and "Sikuli Script is a visual scripting API using Jython to create automation scripts."

Selenese is a set of commands for writing Selenium tests in tabular form. You can read more about it in this StackOverflow post.

Answer 2

Let me try to explain this in simple words so that we don't get confused with different jargon used with Selenium.

• Selenium 2 API, (Google) WebDriver, Selenium WebDriver are same things. Why we call it Selenium WebDriver because it is combination of Selenium (from ThoughtWorks) and WebDriver (from Google). We call it Selenium 2 also since WebDriver provides backward compatibility to Selenium 1. So if you want to start with automation, better to start with WebDriver.

• Selenium Grid is used for running automation in parallel mode. Suppose, we want to run a test on 3 browsers; IE, FF, Chrome, we use Grid.

• Selenium/Webdriver supports different testing frameworks (FW). These are different Unit Testing frameworks Selenese PHPUnit, NGUnit, HtmlUnit, HttpUnit, JUnit. Depending on the application, different FW have different benefits. We should thorough study our application and then choose FW appropriately.

• Selenium/Webdriver also supports different languages. So we can choose any language to write our script.

My personal opinion is: Selenium/Webdriver is best fit with Java language as it is written in Java and with we can use testing framework Junit or testNG.