There are important and significant differences between manual and automated testing. Manual testing of embedded systems is most useful in situations where the results of a specific and limited set of test cases are needed relatively quickly. Automated testing, on the other hand, requires a greater initial effort to plan, organize, and produce the tests. The key to achieving a high return on investment in test automation and automated test tools is to plan very carefully. One of the reasons manual testing continues to be performed is because of the relatively quick feedback it produces.
Automation requires an initial investment of time.
Advantages of automation are reduced test cycle calendar time and reduced staff time to run the tests. A reduction in test run time increases test development time. Increased test development time results in increased test coverage quality and earlier defect detection and correction. It also affords the ability to conduct more extensive testing by running a greater number of test cases, thus increasing the quality and reliability of the products. Other advantages of automation include repeatability, leveraging and accumulation.