Code Coverage Vs. Test Coverage

Improving the ‘quality’ of software is the key to creating a loyal customer base and increasing the ROI. There are different metrics to assess the software quality, the most important ones are code coverage and test coverage. Sometimes both are used interchangeably, however, they are not the same. Both are used to measure the effectiveness of the code, hence, giving a clear picture of the quality of the software and deciding if the product is ready for deployment.

As code and test coverage are necessary to evaluate the efficiency of the code used in developing the software; let’s shed light on how code coverage and test coverage differ from each other and help in providing an insight to the software quality.

What is Code Coverage?

Code coverage is performed to analyse the code execution length. It is a software testing practice that determines the extend to which the code has been executed by observing the critical lines in the code across the length. Further, it helps in validating the code for understanding the robustness of the final outcome.

Code coverage is a white-box testing technique that generates a report that details how much of the application code has been executed, making it easy to develop enterprise-grade software products for any software company.

How is Code Coverage Performed?

Code coverage is fundamentally performed at the unit testing level by considering various criteria. Here are a few critical coverage criteria that most companies practice:

Function Coverage: covers the functions in the source code that are called and executed at least once.

Statement Coverage: covers the number of statements that have been successfully implemented in the source code.

Path Coverage: covers the flows containing a series of controls and conditions that have operated well at least once.

Branch Coverage: covers the decision control structures like loops that have been executed without errors.

Condition Coverage: covers the Boolean expressions validated and performs both TRUE and FALSE as per the test runs.

Loop Coverage: covers the completed loop body zero times, exactly once or more than once.

What is Test Coverage?

Unlike code coverage, test coverage is a black-box testing procedure that provides data about the tests performed on an application or website. It controls the number of tests that have been completed by deciding the area of a requirement not executed by a set of test cases.

Test coverage helps to create additional test cases to ensure the maximum range of requirements is outlined in multiple documents like:

  • FRS (Functional Requirements Specification)
  • SRS (Software Requirements Specification)
  • URS (User Requirement Specification)

Additionally, it helps identify a quantitative measure of test coverage, which is an indirect method for quality checks.

How is Test Coverage Performed?

Test coverage can be accomplished by practicing static review procedures like peer reviews, inspections, and walkthroughs by transforming the ad-hoc defects into executable test cases.

It is performed at the code level or unit test level using automated code coverage or unit test coverage tools. In contrast, functional test coverage can be done with the help of proper test management tools.

Here are a few critical coverage criteria that most companies practice:

  • Functional testing: Functional testing evaluates the features against requirements specified in the Functional Requirement Specification (FRS) documents.
  • Acceptance testing: Acceptance testing verifies whether a product is suitable to be delivered for customer use.
  • Unit testing: Unit testing is performed at the unit level, where the bugs are extensively different from problems found at the integration stage.

Significant Differences Between Code Coverage and Test Coverage

Here are some of the prime differences between code and test coverage:

Code Coverage Test Coverage
Refers to which application code is exercised when the application is running Refers to how well the Number of tests
executed covers the functionality of an application
Helps in measuring how efficiently the test execution can be achieved Provides new test cases, which helps to improve the test coverage and, in return, increases the defects
Checks the quantitative measurement Helps identify the measure of test cases, which enhances the quality of the software
Helps in testing the source code Eliminates test cases that are not useful and do not increase the test coverage of the software
Defines the degree of testing Helps find the areas that are not implemented by any test cases
Performed by developers Performed by the QA Team

Method to Calculate Code and Test Coverage

The formulas for calculating various coverages of code are:

Code Coverage

Statement Coverage can be calculated as the number of executed statements/Total number of statements X 100

Function Coverage can be calculated as the number of functions called/Total number of functions X 100

Branch Coverage can be calculated as the number of executed branches/Total number of branches X 100

Example: If the total number of executed branches are 6 and the total number of branches is 7, then the branch coverage will be 6/7*100 = .85

Test Coverage

In the first step, calculate the total number of lines in the software under test.

Then in the second step, calculate the number of lines of all the codes of all the test cases currently under execution.

Then divide the count in step one by count in step two.

The result is then multiplied by 100 to get the percentage of test coverage that is covered. 

Example: If the total number of lines in a code is 500 and the number of lines executed in all is 50, the test coverage is 500/50 * 100 = 10%.


In this fast-paced, technology-driven world, understanding code coverage and test coverage are necessary for developers and testers. These coverages help strengthen and simplify the code so that the resulting application is the highest possible quality. However, developers and QAs can build result-driven, modern code that sets the foundation of genuinely great software by executing these concepts.