1. Structural quality verification
   This test verifies that all menus, links, and anchors are available at proper positions and are functional to take the user to the correct location. Websites may contain non-HTML (such as Flash) controls that also need to be tested.
   
2. Content validation
   This is to ensure that the static pages have the same content every time. The dynamic pages should produce the same content for given inputs. With the rise of AJAX-based web pages, content validation has become increasingly challenging.
3. Input validation
   This test validates that the input provided by users is correct and safe. The possible number of input combinations that thousands of users can make is huge, hence the need to test as many combinations as possible.
4. Functional validation
   This test validates that the website features can be used as per the use case scenarios. It is important to cover as many usage paths as possible. Further, there is a need to test scenarios in which the user does not take the expected path and check that the application does not crash.
5. Security validation
   This checks that the access to website content is secured, the website is not prone to malicious inputs, and does not give away internal details.
6. Browser independence testing
   This test checks that the website behaves identically on various supported browsers (e.g., IE, Firefox, and Safari) on the supported platforms (e.g., Windows, Linux, and Mac).
7. Performance testing
   This test verifies that the website behaves (responds) appropriately when numerous users on the website.

Open Source Testing Tools
There are several open source tools available that help automate and execute web tests conveniently and provide useful reports on test results. Some of these tools are described below. Specific tools exist for specific needs; you can choose different tools based on the capability and ease of usage.

HttpUnit
HttpUnit emulates the relevant portions of browser behavior, including form submission, JavaScript (limited not full), basic http authentication, cookies, and automatic page redirection. It allows Java test code to examine returned pages either as text, an XML DOM, or containers of forms, tables, and links.

HtmlUnit
HtmlUnit is a "browser for Java programs." It is not a generic unit testing framework but a specific way to simulate a browser for testing purposes. It’s intended to be used within another testing framework such as JUnit or TestNG.

Selenium
Selenium is a testing tool for web applications. It runs directly in a browser. Selenium includes:

• Selenium IDE: An add-on to Firefox used for recording test scripts.
• Selenium Core: Client-side testing support for web applications added directly to the application.
• Selenium RC (Remote Control): A Java server used for the execution of test scripts.

Jameleon
Jameleon is an automated testing framework that manages test execution and reporting. This framework provides the flexibility to use plug-ins to test various applications such as web, desktop, database, and even mainframe. Some of the most used plug-ins is Jiffie (drives Internet Explorer), HTTPUnit, HtmlUnit, and Selenium (drives multiple browsers using Selenium Remote Control application).

TestSmith
TestSmith is a simple Windows application that captures and replays the activities on the browser and also multiple applications in the same session. This is free software.

Apache JMeter
JMeter is a Java desktop application designed to load test functional behavior and measure performance. Apache JMeter is used to test performance both on static and dynamic resources (files, servlets, Perl scripts, Java objects, databases and queries, FTP servers, and more). It can be used to simulate a heavy load on a server, network, or object to test its strength or to analyze overall performance under different load types. In addition, JMeter is used to make a graphical analysis of performance or to test the server/script/object behavior under heavy concurrent load.

OpenSTA
OpenSTA (Open System Testing Architecture) is distributed software architecture for developing, executing, and analyzing the test results. It is capable of performing scripted HTTP and HTTPS heavy load tests with performance measurements from Win32 platforms.

A test may include scripts or collectors or both. Scripts define the operations performed by virtual users. Collectors define sets of SNMP, NT performance data, or other data to be retrieved during all or part of a test run. They can provide useful information about system activity and the results can be analyzed alongside those from other OpenSTA modules.

Table 2 provides a list of open source tools discussed, their test and tool category, along with their usage.

Let’s put the usage of discussed tools in perspective with a hypothetical example.

Business Case
A website under development needs to be tested. The website has a rich user interface including Flash and AJAX-based controls. This is to be supported on multiple browsers on different platforms. In addition, you need to test the web server response under load to verify the scalability.

Suggested Solutions

• For structural validation use HttpUnit or HtmlUnit tools and for Flash-based controls use TestSmith.
• For content/input/functional validations you can use Jameleon or Selenium. Both of these tools are very useful as they allow the use of custom tags in tests.
• Selenium is useful if you need to support multiple browsers.
• For performance testing you can employ OpenSTA.
• All of these tools have a command-line interface. You can easily create a test framework that will contain different tools as components. Create a test driver application that will run all the tests based on various tools.

Conclusion
Considering the importance and nature of websites, testing is an important part of the development cycle. Considering the complexity in terms of number of browsers, platforms and tests, automating website testing is essential. There are many open source tools that help automate website testing. You can customize, configure, and integrate these tools to develop a cost-effective and comprehensive test solution.