Test Coverage

Software testing ensures that you get a high quality software application that fulfill your desired business goals and objectives. It is a huge field containing a lot of important aspects that every professional tester should consider while testing the application, and one of those important aspects that many of the beginner testers often overlook is a “Test Coverage”.

Are you a beginner tester willing to explore more about test coverage, issues and benefits associated with it? If yes, then this article brings everything you may wish to know about it!
Well, test coverage is an important indicator of software quality and a vital part of software maintenance. It helps testers evaluate the effectiveness of testing by bringing data on different coverage items. However, most of the research efforts have been put on how to coverage information by either code-based testing or requirement-based testing.

So, what is test coverage?

Test CoverageTest coverage generally measures the amount of testing performed by a specific set of test. Test coverage can be used anywhere where we can actually count things and can evaluate whether or not each of those things have been tested by some test. Generally, a good testing will help you get almost 80%-90% of test coverage.

However, if you’ve achieved 100% test coverage, that doesn’t mean your application 100% test. If you’re achieving 100%, it is sure that you’re aiming for higher number rather than focusing on the quality. Moreover, the effectiveness of the other defects metrics depends on the test coverage you’re getting.

What are the issues associated with test coverage?

  • It is important for the testers to reach high levels of test coverage because people want to know if they are testing enough or not. Whenever you get test coverage less than 50%, it is a red alarm for you. However, it is important to know that test coverage never determine the sufficiency of testing.
  • Is it possible to know when testing is enough or need more? Well, it is possible to predict that whether testing is enough or not in two possible scenarios. The first one is when you don’t get errors that escape within the production, and the second one is when there is not many cases when you have to modify the code in order to avoid production defects caused by that code.

Analysis of your coverage will help you identify parts of your code haven’t been tested yet, but if you’ve some problem or weakness in your test suit that you can detect using coverage, then it is possible that it remains weak if coverage fails to detect it. This means it is not always successful to help you detect defects left out earlier. So, what are the benefits and drawbacks of test coverage in software testing?


  • In order to expand coverage, it creates some additional test cases. By doing so, it will help you leverage from the maximum number of defects found that was left out earlier in test cases.
  • Test coverage can help testers to identify and detect areas of a program that has left out by a test case created earlier.
  • It helps you evaluate the quality of the application or product indirectly with the help of determining a quantitative measure of the entire code coverage.
  • Make it easy for the testers fix the bugs discovered in covered code.
  • Helps you eliminate dead code within the application.


  • One of the biggest drawbacks of test coverage or code coverage is that it only measures coverage of whatever is written, such as the code itself. This means it fails to convey details about the application or software that has not been written.
  • If you fail to implement any specific function or a function was removed from the specification, it would be impossible for the structured based techniques say anything about such omitted functions.

From the above discussion, it is quite clear that test coverage definitely serves an important role as it will help testers and developers to identify a few of the areas that were left out earlier in the test cases, but it also suffers from a few drawbacks. So, what’s your point of view on this? Share your views in the comments…!

About the author: Prashant Chambakara is a test automation technology enthusiast, loves to share insights, views and information on software testing and its associated branches like automation testing, test automation tools,etc. He is currently working with Cygnet Infotech – a test automation consulting services provider and the parent company of TestingWhiz, a web testing automation tool. Feel free to contact us for testing services. Connect with Prashant on Twitter @prashant_geek.