Software Testing - Code Coverage

Software Testing is a part of the software development life cycle. It has an immense impact on assuring the quality of the software. Software testing is subdivided into various types of testing like unit, system, integration, and acceptance testing which increases the code and test coverages.

What is Code Coverage in Software Testing?

The code coverage in software testing refers to the white box testing methodology done to measure the point to which the code on which the software is built has been tested. This helps in delivering a quality product and quantifies how much the software has been verified.

Not only the testers, the developers are equally responsible for delivering quality software to the customers. By referring to the quality, every aspect of a product consisting of performance, maintainability, reliability, usability, security, and so on are considered. The code coverage is determined by the below formula −

Code Coverage = (count of lines executed)/(count of lines written for the complete software)* 100

Some of the popular tools that can be used for code coverage are Cobetura, Emma, JTest, and so on.

Code Coverage Criteria in Software Testing

There are multiple code coverage criteria in software testing. They are listed below:

Coverage of Blocks or Statements

It determines the count of the statements or blocks executed triumphantly from the complete code of the software. The coverage of blocks or statements can be measured using the below formula −

Statement Coverage = (count of statements executed)/(count of total statements)* 100

Coverage of Branch or Decision

It determines the count of the decision or branch structures executed triumphantly from the complete code of the software. The coverage of branch or decision can be measured using the below formula −

Branch Coverage = (count of decision or branch results obtained)/
   (count of total decision or branch results in software code)* 100

Coverage of Function

It determines the count of the functions that are invoked and executed at least one time from the complete code of the software. The coverage of function can be measured using the below formula −

Function Coverage = (count of functions invoked)/(count of total functions)* 100

Coverage of Conditions

It determines the count of the boolean criteria executed in the conditional statements. The coverage of conditions can be measured using the below formula −

Condition Coverage = (count of operands executed)/(count of total operands)* 100

Advantages of Code Coverage in Software Testing

The advantages of code coverage in software testing are listed below −

The code coverage is done to ensure that the product delivered has the best quality, and performance.
The code coverage is helpful in measuring the extent to which the code has been tested and executed.
The code coverage helps to maintain the application code.
The code coverage helps in code refactoring by identifying the dead, useless, and bad code.
The code coverage helps in addition to new test cases to increase the code coverage.
The code coverage aids in creating more effective test cases.
The code coverage detects defects that remain undetected.

Disadvantages of Code Coverage in Software Testing

The disadvantages of code coverage in software testing are listed below −

The code coverage occasionally fails to cover every line of code for the software.
The code coverage does not confirm that all the features, and aspects of the product have been verified.
For some scenarios, more combinations of inputs or data are required to cover test cases.
The developers need to be acquitted with unit test cases creation to touch every scenario of software code.

Why is Code Coverage Done?

A code coverage is normally done by developers at the time of unit testing. Since the developers themselves create the tests for the code they have developed, they can measure the code coverage in a better way. The developers take the decision if more tests need to be added at the unit testing levels.

As more and more functionalities are added to the product, the unit tests need to be revisited, updated, added, and so on. At the same time, however big the product has been developed, the quality standards have to be followed. The code coverage keeps a check on the quality of code incorporated in the complete development process.

A good measurement from the code coverage metrics signifies lower probability of undetected errors. A threshold code coverage value is set which determines if the software being shipped is fit to be deployed in the production environment.

Differences Between Code Coverage and Test Coverage

The differences between code coverage and test coverage are listed below −

Test coverage is performed with the sole intent of validating if the code developed is working as it is supposed to do. But code coverage is performed to quantify the total number of lines of code executed successfully while testing is performed.
Test coverage is mainly used for test driven development approaches.
Test coverage is adopted at the initial phases of software development life cycle, where the focus is to check if the basic features have been implemented correctly. However, as we progress to the software development life cycle, and the product complexity enhances, code coverage is normally adopted to verify if every nook, and corners of the code have been tested.

The choice of code or test converge varies from project to project based on requirements and strategy adopted for testing. However, a balanced approach of using both test coverage and code coverage metrics as per project needs help to get the optimal benefits from the both.

Conclusion

This concludes our comprehensive take on the tutorial on Software Testing - Code Coverage. We’ve started with describing what is code coverage in software testing, what are code coverage criteria in software testing, what are the advantages, and disadvantages of code coverage in software testing, why code coverage is done, and what are the differences between code coverage and test coverage.

This equips you with in-depth knowledge of Software Testing - Code Coverage. It is wise to keep practicing what you’ve learned and exploring others relevant to Software Testing to deepen your understanding and expand your horizons.