Test automation is the use of software to control the execution of tests, the comparison of actual outcomes to predicted outcomes, the setting up of test preconditions, and other test control and test reporting functions. Commonly, test automation involves automating a manual process already in place that uses a formalized testing process.
Although manual tests may find many defects in a software application, it is a laborious and time consuming process. In addition it may not be effective in finding certain classes of defects. Test automation is a process of writing a computer program to do testing that would otherwise need to be done manually. Once tests has been automated, they can be run quickly. This is often the most cost effective method for software products that have a long maintenance life, because even minor patches over the lifetime of the application can cause features to break which were working at an earlier point in time.
There are two general approaches to test automation:
- Code-driven testing. The public interfaceto classes, modules, or libraries are tested with a variety of input arguments to validate that the results that are returned are correct.
- Graphical User Interface testing. A testing framework generates user interface events such as keystrokes and mouse clicks, and observes the changes that result in the user interface, to validate that the observable behavior of the program is correct.
Test automation tools can be expensive, and it is usually employed in combination with manual testing. It can be made cost-effective in the longer term, especially when used repeatedly in regression testing.
What to automate, when to automate, or even whether one really needs automation are crucial decisions which the testing (or development) team has to take. Selecting the correct features of the product for automation largely decides the success of the automation. Automating unstable features or features that are undergoing changes should be avoided.reference:- http://en.wikipedia.org/wiki/Test_automation