Longer answer: yes, but how easy it is depends on how well structured the application is.
Personally, I rarely test Struts 1 actions themselves--too complicated. Things like StrutsTestCase can help in that regard. The bulk of application functionality, however, should really live in service objects (or whatever terminology you prefer), such that they can be tested outside of Struts, and without the cognitive overhead of mocking the Struts infrastructure. Actions can be tested by something like Selenium, serving the dual purpose of making sure you're getting the right responses back from the action and the correct view is shown in the browser.
posted 9 years ago
But StrutsTestCase can be used only with Struts 2.0 framework I think ,cannot use it with Struts1.