Testing Web Presentation Layer using HtmlUnit - Part I

Presentation-layer testing means finding bugs in the graphical user interface (GUI) of a web application and portlets.

What is HtmlUnit?
HtmlUnit is an open source Java headless browser framework. It allows tests to imitate programmatically the user of a browser-based web application including portlets. HtmlUnit tests don’t display a user interface. The framework lets you test all aspects of a web application.

In the HtmlUnit context “testing with a web browser,” actually means that we’re testing by emulating a specific web browser.

When to use HtmlUnit?
HtmlUnit is a 100 percent Java headless browser framework that runs in the same virtual machine as your tests. Use HtmlUnit when your application is independent of operating system features and browser-specific implementations not accounted for by HtmlUnit, like JavaScript, DOM, CSS, and so on.

Benefits

• More efficient than manual testing
• Less error prone than manual testing
• Enables collective code ownership
• Enables refactoring
• Enables frequent integration
• Enables browser-specific testing  with less effort
  

Summary

• HtmlUnit is a 100 percent Java solution with no external requirements; it offers a complete HTML object model, which, although creating rather verbose test code, offers great flexibility. 
• Use HtmlUnit when your application is independent of operating system features and browser-specific implementations of JavaScript, DOM, CSS, and so on.

References

• http://htmlunit.sourceforge.net/
• JUnit in Action, Second Edition