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code coverage vs test coverage

Code Coverage vs Test Coverage

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Introduction:

Code coverage and Test Coverage are two key aspects of Software Testing. To ensure that software testing is successful, developers and testers must have sufficient code coverage and maximum test coverage. A good Quality of Code and Test Coverage ensures that the software applications work smoothly and result in higher customer acceptance. In this blog, we will examine a comparative study of code coverage and test coverage.

Code Coverage

Code Coverage is a type of White Box Testing Technique performed by developers to check the correct execution of code. For the development of a good software application, it is essential for developers to ensure that the application has maximum code coverage, especially proper coverage of source code since source code is the most important part of a software application. To ensure proper coverage of codes, developers use various Code Coverage tools. 

Reasons for Performing Code Coverage

Code coverage is mostly performed by developers during unit testing. Developers perform unit test cases which help them to decide what all test scenarios can be covered in unit testing. Through code coverage, developers get to know whether sufficient test scenarios are covered in unit testing as well as the number of more test scenarios to be covered in unit testing. With the progress in software development, new functionalities get added, and old features get removed. To meet the changes in functionalities it is necessary to frequently change the code.

Code coverage ensures that the application contains only the proper relevant code before being sent into the production stage. A good code coverage ensures lower chances of bug detection. To ensure smoother code coverage, developers use various code coverage tools like Jacoco, Cobertura, Clover, etc. Code Coverage tools help remove unidentified bugs at an early stage of software development and eliminate code repeatability. Code coverage tools work by analyzing the various codes of software applications as well as their implementation. Code coverage tools also create reports detailing the coverage of code done in the software application.

Advantages of Code Coverage

The following are the advantages of code coverage

  • Error elimination- Good code coverage results in the identification of errors in the early stages of software development as a result those errors could be fixed resulting in the development of good-quality software applications.
  • Removal of unnecessary test cases- Through code coverage developers can find out the test cases which are not needed for software application development thus making it easier for testers to test the software application.
  • Removal of unwanted codes: Code coverage helps to explore all unwanted codes of the application resulting in the removal of those unwanted codes which might after badly affect some or all functionalities of the application.
  • Increase speed in the software development process: Code coverage results in making the software application development process faster thus ensuring more software applications are developed and delivered within a short period thereby increasing the productivity of organizations.
Levels of Code Coverage

The following are the various levels of code coverage:

  • Branch Coverage: Branch Coverage refers to covering every section of code coverage. Suppose for example the tester provides an alternative way for testing the browser compatibility where instead of using only the if statement, if else, or do while is used, Branch coverage ensures that all those branches like if, if else, do while are covered successfully.  
  • Function Coverage: Function coverage ensures that all the functions are successfully tested with the same test inputs as well as with different inputs. It also includes testing of programming logic with same as well as different inputs.
  • Statement Coverage: Statement coverage is done to ensure every statement of source code is being executed successfully without much trouble.
  • Loop Coverage:  Loop coverage ensures that every loop associated with the source code of an application is successfully executed without detection of bugs in the early stages of software development. Care should be taken to perform loop coverage of those particular loops whose performance is based on output as runtime so as to strengthen the source code. 
  • Condition Coverage: Conditional coverage is mostly used in conditional statements ensuring syntax and variables are correctly written as well as various operators like ‘<’,’<=’,’>’,’>=’, AND, OR, and NOT are used in appropriate places before code execution.
The schematic representation of various levels of code coverage is mentioned below:
code
Code Coverage Tools

Some of the commonly used code coverage tools are mentioned below:

code 2
Test Coverage

Test Coverage is basically a black box test technique performed by testers where code is not visible while performing testing. It refers to the number of test scenarios covered as well as the test cases written for every test scenario in a software application. Since test scenarios come from requirements, test coverage ensures that the maximum requirements are covered while testing the software applications before release into production.  These requirements are covered in three different documents which are as follows:

  • Functional Requirement Specification(FRS)
  • Software Requirement Specification(SRS)
  • Customer Requirement Specification(CRS) 

Testers also use various Test Coverage tools like TestNG, Junit, and Pyunit for faster and more effective test coverage. Finally Test Coverage report is prepared containing detailed information about the test coverage performed on the specific parts of the software application. It also details information about the test scripts executed on a software application or website.

Test Coverage Tools

Some of the commonly used test coverage tools are mentioned below:

code
Advantages of Test Coverage

The advantages of test coverage are:

  1. Test coverage gives information about those portions of the code where test scenarios and test cases are not covered.
  2. Test Coverage results in the elimination of unnecessary test cases and coverage of mostly basic and critical features of software applications.
  3. Test coverage ensures that any critical and severe bugs are detected at an early stage of software development.
  4. Test coverage helps developers to design more effective and innovative test cases.
Mechanisms Of Test Coverage

The various mechanisms of test  coverage in sequential order are

  • Unit Testing: The unit is the smallest component of the software application. So unit testing refers to checking the functionality of software applications as well as detecting the presence of bugs at the unit level.
  • Functional Testing: Functional test coverage refers to testing the features of software applications as per the requirements mentioned in the Functional requirement specification document.
  • Integration Testing: Integration testing coverage refers to testing the data flow between two or more modules.
  • AcceptanceTesting: Acceptance testing refers to end-to-end testing of software applications based on customer real-time business requirements. A specific group of customers who know about the software application perform acceptance testing by looking at the Customer Requirement Specification Document. Through acceptance testing, it will be known whether a software application is ready to be released into the market.

 

The schematic diagram of different testing mechanisms is shown below

code
Types Of Test Coverage

The various types of test coverage are:

  • Features Coverage: Features refer to the functionalities or components of an application. Test cases are written to ensure that maximum functionalities of software applications are covered. For example in the login functionality of Facebook, the user needs to enter a valid username and valid password in order to login to the Facebook application. If any of the username name or password is incorrect then the user should not be able to log in to the Facebook application, instead an error message should be displayed.  
  •   Risk Coverage: Every software application has some risk associated with it. Even though it is not possible to completely remove the risks of software applications, however, it is necessary to remove maximum risks that can potentially affect the basic and critical functionalities as well as the security of the application. Risk Coverage also involves setting up proper infrastructure for servers for developing any websites to ensure every page of the website is accessible at high speed.
  • Requirement Coverage: Requirement coverage is an essential part of test coverage which refers to covering maximum requirements mentioned in the product requirements specification documents. For example, to test Amazon commerce application in a country whose official language is Chinese it is necessary that the default language of the application is set to Chinese.

 The schematic representation of different types of test coverage is shown below

code
The choice between Code Coverage and Test Coverage

Although code coverage and test coverage are completely different from each other, it is not appropriate to make a choice between the two. Both Code  Coverage and Test Coverage are integral parts of software application development. However choosing between code and test coverage solely depends on requirements, but in most scenarios both code and test coverage become important. If the motive is to ensure that the code is working perfectly fine then test coverage is more appropriate to be used whereas if the aim is to ensure proper execution of code during testing, then code coverage is chosen in such scenarios. If Test Driven Development approach is chosen then test coverage becomes more important. In the case of early stages of software development, test coverage becomes important for ensuring that basic and critical features of the software are working as per requirements. In later stages of software development code becomes lengthy and complex and as a result code coverage becomes important to ensure that the codes are properly covered.

Conclusion

Code coverage and Test coverage are both important components of software applications. Although it is not possible for 100 percent code coverage and test coverage in a software application, it is still a necessity for software developers and testers to ensure maximum code and test coverage for delivering a quality software application to customers. It is also important for developers and testers to have a thorough understanding of code coverage and test coverage which can save a lot of time and resources that otherwise would have been spent in software development.

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