Test coverage or code coverage is a term widely used in software testing services and is considered a part of software maintenance. It is a very useful tool that lets software testers identify untested areas of a code base. By providing data on different coverage items it helps in evaluating the effectiveness of testing.
Together with covering those areas that have not yet been tested, test coverage also helps to monitor and maintain the quality of testing. Measuring test coverage quantitatively will help to determine its quality, as they are indirectly related. It also helps to identify redundant test cases that prevent any increase in coverage thereby providing better software testing services.
How can the output of test coverage help?
- Test Coverage helps to measure traceability between requirements and test cases.
- With the availability of a proper Test mechanism, change tracking and impact analysis will become more effective.
- With proper Test Coverage, defect leakages can be easily prevented.
- It gives an easy way to find gaps in requirements, test cases and defects at unit level.
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Tools for Test coverage
The Test Coverage tools are useful as they can easily locate application functionalities and allows exercising the functionalities of interest. What part of the application code is executed will be indicated by the test coverage tool. This helps to easily locate functionality in a very effective manner, especially those in a large, difficult to understand system. Coverage tools help in checking how thoroughly testing has been done.
- Helps to identify coverage items.
- It lets you calculate the percentage of coverage items that were tested by a set of tests.
- It reports on the coverage items that haven’t yet been tested.
- Generate stubs and drivers.
It is very important to know that achieving 100% statement coverage doesn’t mean that your software is completely tested and error free. This is because coverage tools can only measure the coverage for those items that they can identify. Coverage tools needs to be run often to look at these bits of untested code.
Benefits of Test Coverage
- Helps identify defects during the early stages of a project life cycle.
- In order to increase coverage, additional test cases are created.
- Provides a considerable reduction in UAT defects and production defects which helps achieve a better ROI.
- It helps in finding areas of a program that are not exercised by a set of test cases
- Full control over time, cost and scope.
- Managing the Risk based testing approach makes testing life smoother.
- Determining the quantitative measure of code coverage measures quality of the application or product indirectly.
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Drawback of code coverage measurement:
- It can measure only the coverage of what has been written. This means that the code itself cannot say anything about the software that has not been written.
- It can only look at a structure which is already there. If a specified function was omitted or function has not been implemented, then structure-based techniques cannot say anything about them.