What Is Test Coverage And Why Do I Need It?
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What Is Test Coverage And Why Do I Need It?

Review the benefits of Test Coverage and be ready to take the next step! Are you ready to invest in your business?


Test coverage is an important part of Agile Software development, testing and maintenance. It is the measure of effectiveness of the testing by providing data on different items. The amount of testing performed by a set of test cases is called Test Coverage. By the amount of testing we mean that what parts of the application program are exercised when we run a test suite. In other words, test coverage is defined as a technique which determines whether our test cases are actually covering the application code and how much code is exercised when we run those test cases. 


Test coverage measures the amount of testing performed by a set of test cases. whenever we can count things and can tell whether or not each of these items has been tested again by some test cases, then we can measure coverage and is known as test coverage.


When we can count upon certain aspects in an application and also tell whether the test cases are covering those things of application, then we can say that we measure the coverage. So basically the coverage is the coverage items that we have been able to count and see what items have been covered by the test. The test coverage by two test cases can be executed the same but the input data of 1 test case can find a defect while the input data of a 2nd cannot. So with this we understand the 100% coverage does not mean 100% tested.


Mainly more focus is put on getting code coverage information by code based testing and requirement based testing but not much stress is put on analysing the code coverage by covering maximum items in code coverage.



Requirements, structure and architecture are three software abstractions which are used to develop and build the software. These can be described as the “size of the software” With these we can determine the completeness criteria with ease. Here are some examples of metrics of software testing:

  • REQUIREMENTS COVERAGE: The metrics used here is to ensure if the software has been tested for all requirements for normal range of us, abnormal or unexpected usage and techniques of requirement coverage. Usual techniques involve is to test the normal range and robustness coverage of software requirements and Software designs.
  • STRUCTURAL COVERAGE: You need to measure if each element of the software has been exercised during testing. Test coverage is a structural coverage testing approach that includes Code statements, Conditions & Decisions.
  • ARCHITECTURAL COVERAGE: Measuring how much actual control and data links have been utilised during testing. This involves using techniques such as Data Paths and Control links.


We perform test coverage analysis in order to find areas in specified requirements which are not covered by the test scenarios and cases. By determining the test coverage we can create more test cases to increase our test coverage. By performing the test coverage we can measure how much testing is covered. This indirectly means that we are qualifying the quality of the application.  We then identify some useless test cases which don’t have meaning in being executed and thus remove them. This allows testing life to become a smooth process by managing the risk based testing approach.  Traceability between the requirements and the test cases can be achieved and when proper test coverage is implemented, we can determine impact analysis and change tracking.

Test coverage can best me measure by following these principles:

  • Mapping the requirements to the test cases.
  • Testing the case status
  • Code coverage analysis


When implementing test coverage we can actually determine which part of the code was touched for the deployment/release. Here are some advantages of implementing test coverage:

  • Prevent defective leakage using test coverage analysis.
  • Defects can be prevented during the early stages of an application life cycle.
  • You will not build up technical debt, save resources, time and the scope will be fully in control.
  • The test coverage analysis can determine the decision points and important navigation created in the application which helps us to increase the test coverage.
  • Determine which navigations in the code are not tested yet.
  • Determine the quality of the testing we are performing.
  • Finding gaps in requirements become an easy aspect of development. Test cases and defects will be found during the early stages of the application development life cycle.


Test coverage is a very important aspect of software development testing, however there are some aspects of test coverage that you need to take into consideration:

  • Test coverage finds gaps in the application code that already has been written. You are able to test it and measure it and implement navigation points created in the application. However, there is no measurement for the part of software that has not been coded yet, allowing you to only measy the written part.
  • That also applies to the situation where a specification that has not been implemented yet or has been removed. Test coverage will not inform you about anything other then the structure of the code which needs to be written and present.


Test coverage can be implemented by static testing techniques. These testing techniques include peer reviews, code inspections and code walkthroughs. We can convert the adhoc defects into test cases and analyse test coverage. We can use code level tools and automation to achieve test coverage at unit level. Test management tools like a Bi-directional traceability matrix are used to perform functional test coverage which will establish traceability between requirements, defects and test cases. The best practices of test coverage involve performing maintenance and cleanup activities at frequent intervals of time. Maintaining metrics to measure the test coverage percentage are a very important aspect as well. Use test management tools, it allows you to have control over all aspects of coverage from requirements, test cases and defects. Quality gate mechanism should be proper to verify the results.


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