Software testing is the process of executing a program with the intention of finding errors in the code. It is the process of exercising or evaluating a system or system component by manual automatic means to verify that it satisfies specified requirements or to identify differences between expected and actual results [4]. Software Testing should not be a distinct phase in System development but should be applicable throughout the design development and maintenance phases. ‘Software Testing is often used in association with terms verification & validation ‘Software testing is the process of executing software in a controlled manner, in order to answer the question: Does the software behave as specified. One way to ensure system‘s responsibility is to extensively test the system. Since software is a system component it requires a testing process also. / Software can be tested either manually or automatically. The two approaches are complementary: automated testing can perform a huge number of tests in short time or period, whereas manual testing uses the knowledge of the testing engineer to target testing to the parts of the system that are assumed to be more error-prone. Despite this contemporary, tools for manual and automatic testing are usually different, leading to decreased productivity and reliability of the testing process. Auto Test is a testing tool that provides a “best of both worlds” strategy: it integrates developers’ test cases into an automated process of systematic contractdriven testing. This allows it to combine the benefits of both approaches while keeping a simple interface, and to treat the two types of tests in a unified fashion: evaluation of results is the same, coverage measures are added up, and both types of tests can be saved in the same format. The objective of this paper is to discuss the Importance of Automation tool with associate to software testing techniques in software engineering. In this paper we provide introduction of software testing and describe the CASE tools. The solution of this problem leads to the new approach of software development known as software testing in the IT world. Software Test Automation is the process of automating the steps of manual test cases using an automation tool or utility to shorten the testing life cycle with respect to time.