The PLC and Automated Test
A product's stages of development are referred to as the product life cycle (PLC). There is considerable work involved in getting a product through its PLC. Software testing at many companies has matured as lessons have been learned about the most effective test methodologies. Still, there is a great difference of opinion about the implementation and effectiveness of automated software testing and how it relates to the PLC.
Computers have taken over many functions in our society that were once "manual" operations. Factories use computers to control manufacturing equipment and have cut costs enormously. Electronics manufacturing use computers to test everything from microelectronics to circuit card assemblies. Since automation has been so successful in so many areas, does it make sense that a software program should be used to test another software program? This is referred to as "automated software testing" for the remainder of this article.
Software testing using an automatic test program will generally avoid the errors that humans make when they get tired after multiple repetitions. The test program won't skip any tests by mistake. The test program can also record the results of the test accurately. The results can be automatically fed into a database that may provide useful statistics on how well the software development process is going. On the other hand, software that is tested manually will be tested with a randomness that helps find bugs in more varied situations. Since a software program usually won't vary each time it is run, it may not find some bugs that manual testing will. Automated software testing is never a complete substitute for manual testing.
There has been plenty of debate about the usefulness of automatic software testing. Some companies are quite satisfied with the developer testing his/her own work. Testing your own work is generally thought of as risky since you'll be likely to overlook bugs that someone not so close to the code (and not so emotionally attached to it) will see easily. As soon as the developer says it's done they ship it. The other extreme is the company that has its own automatic software test group as well as a group that tests the software manually. Just because we have computers does that mean that it is cost effective to write tests to test software and then spend time and resources to maintain them? The answer is both yes and no. When properly implemented, automated software test can save a lot of time, time that will be needed as the software approaches shipping.
This is where the PLC comes in. How effectively you make use of the PLC will often be dependent on your programming resources and the length of the PLC. Companies large and small struggle with software testing and the PLC. Hopefully, this discussion of the PLC should help you determine when to use automation and when manual testing is preferred. This should help you answer the questions: "Why should I automate my software testing?" "How can I tell if automation is right for my product?" "When is the best time to develop my test software?".