Selenium vs Low/Network level tools like Webtest/HttpUnit/HtmlUnit(java)
If you are using a "low/network" level tool like htmlunit then it
has the advantage of being fast - but its javascript will
not work work in most complex websites(besides not being a browser test)
Selenium(java, .net) code also has the disadvantage of being dependent on RC server(not big deal).
You should continue low level tools like httpunit etc to use
it for monitoring - but don't use those tools for browser/regression testing.
Selenium vs Watir
If you like your test cases in Ruby (or maybe .net) and are willing to
dig through "hard to understand" documentation - then Watir is a tool
for you.(if you are perl/php/java shop - don't even bother considering Watir
for now)
Watir does have advantage that its recorder uses IE to record.
With Selenium - if your site does not work with Firefox - you will
have to manually write the code(not big deal)..
But the biggest advantage of Selenium is its support for FIT HTML
and the vast languages/browsers/platform that it supports.
(with good documentation)
But maybe things may change in future.
Selenium vs Imacros
Imacros appeared better in recording. But overall its not as powerful for automation(or scheduling).
Selenium vs Dejaclick
Dejaclick has great IDE. However again Selenium beats DejaClick in overall features.
Dejaclick Advantage:
It nicely plays back the recorded stuff - by highlighting appropriate items in green.
It can easily record flash/silverlight - by recording position.(however it may mean that it may not
nicely work in all computers)
It has facility to encrypt sensitive data in your file.
Dejaclick easily allow you to bookmark your script. So that you can play it back in one click.
Disadvantage:
For automation you have to rely on paid site alertsite (AlertSite provides great facility
for running your script at specific cities/region in US. This will allow you to monitor what
your CDN or what the website is serving across different regions)
Watir本质上就是封装了IE COM接口的Ruby库。
Watir is a Ruby library that wraps the COM interface to Internet Explorer. COM is a long-standing Windows-based technology for making libraries accessible to various languages. This allows access to the Document Object Model (DOM) so it doesn’t matter where on the page an object exists, what matters is how you identify it (id, name, title, etc).
Selenium驱动浏览器的方式与Watir不一样，Selenium的自动化引擎是用JavaScript写的，并且运行在浏览器内。
Selenium uses a unique mechanism for driving browsers. Selenium’s automation engine is written in JavaScript and runs inside a browser. The engine, called a browser bot, is embedded in a page that accesses the application under test in a separate frame. Because of cross-site scripting, Selenium’s browser bot has to be served from the same site as the application under test – requiring installation on the server.
Selenium支持命令语言，称为“Selenese”。
Selenium supports a command language, called Selenese. Tests can be embedded in an HTML table, which will be read in by the browser bot and then executed.
Watir和Selenium都是直接在浏览器中执行测试，并且可以在浏览器最小化的状态下运行。
Both tools run tests directly in a browser, and both do it in a way that allows the browser to be minimized while the tests are running, which means you don’t have to dedicate a machine to running tests.
Watir采用Ruby语言，容易学习，起先仅支持IE，现在支持FF。
Watir was designed to be easy to learn, it allows page elements to be identified by index, name, ID, value or adjacent text. Complaint: Watir is currently limited to IE browsers on Windows. There are efforts underway to support Firefox in the future.
Selenium一开始就设计成支持多浏览器和多平台。Selenium需要服务器端安装。
Selenium was designed for breadth of coverage- multiple browsers and platforms. It was expected to be used by the same developers who built the application. Complaint: Selenium requires a server-side installation.
Selenium支持多种编程语言。
You can also express Selenium tests in a programming language, taking advantage of language-specific drivers that communicate in Selenese to the browser bot.