Automation Testing 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.
Over the past few years, tools that help programmers quickly create applications with graphical user interfaces have dramatically improved programmer productivity. This has increased the pressure on testers, who are often perceived as bottlenecks to the delivery of software products. Testers are being asked to test more and more code in less and less time. Test automation is one way to do this, as manual testing is time consuming. As and when different versions of software are released, the new features will have to be tested manually time and again. But, now there are tools available that help the testers in the automation of the GUI which reduce the test time as well as the cost, other test automation tools support execution of performance tests.
Many test automation tools provide record and playback features that allow users to record interactively user actions and replay it back any number of times, comparing actual results to those expected. However, reliance on these features poses major reliability and maintainability problems. Most successful automators use a software engineering approach, and as such most serious test automation is undertaken by people with development experience.
A growing trend in software development is to use testing frameworks such as the xUnit frameworks (for example, JUnit and NUnit) which allow the code to conduct unit tests to determine whether various sections of the code are acting as expected in various circumstances. Test cases describe tests that need to be run on the program to verify that the program runs as expected. All three aspects of testing can be automated.
Another important aspect of test automation is the idea of partial test automation, or automating parts but not all of the software testing process. If, for example, an oracle cannot reasonably be created, or if fully automated tests would be too difficult to maintain, then a software tools engineer can instead create testing tools to help human testers perform their jobs more efficiently. Testing tools can help automate tasks such as product installation, test data creation, GUI interaction, problem detection (consider parsing or polling agents equipped with oracles), defect logging, etc., without necessarily automating tests in an end-to-end fashion.
Disadvantages of Automation:
Test automation is expensive and it is an addition, not a replacement, to manual testing. It can be made cost-effective in the longer term though, especially in regression testing. One way to generate test cases automatically is model-based testing where a model of the system is used for test case generation, but research continues into a variety of methodologies for doing so.