Code Coverage vs Test Coverage_ A Complete Guide.pdf

Code Coverage vs Test Coverage: A
Complete Guide
Test coverage and code coverage are essential tools to analyze the software and measure the
effectiveness of its codebase in development. They could be interchangeable, but they are
different. This article explains what makes them different to help your understanding.
What is Code Coverage?
Code coverage is a white-box testing technique. It verifies the extent to which developers have
executed the code. The tools used for code coverage contain static instrumentation. Testers can
use these to insert statement monitoring code execution at crucial points in the code.
While adding instrumentation does increase the test execution time and code length, the
information received by the tester due to this more than justifies the increase. Testers receive a
report from the code coverage scripts detailing the extent to which the developers have
executed the application. Testers will analyze the result to understand the product, make their
tests effective, and reduce possible defects after release.
Why perform Code Coverage?

Developers perform code coverage at the unit test level; this gives them a great vantage point to
help them decide the tests they need to include. Code coverage helps them answer questions
like:
● Does the unit test suite have enough tests?
● Has the code been implemented intentionally?
Further, as development progresses, developers add new features and fixes to the codebase,
changing the code to stay updated with these changes while trying to maintain the established
testing standards. Code coverage ensures developers maintain these standards, and only
optimal quality code remains.
A higher code coverage percentage means lesser chances of overlooking unidentified bugs. It
helps when you set up a minimum level that code coverage must achieve to reduce the chances
of finding bugs at later stages of the development process.
Code Coverage Best Practices
1. Aim for Balanced Coverage Goals: Avoid setting an arbitrary 100% coverage goal, as
it can lead to unnecessary tests that may not add value. Instead, aim for practical,
high-impact coverage percentages that ensure critical areas are covered.
2. Measure Relevant Metrics: Depending on your application requirements, focus on
different coverage types, such as statement, branch, and path coverage, to ensure that
all code paths have been adequately tested.
3. Identify Gaps Early: Use code coverage tools to identify areas with low coverage during
development. This will help address them proactively and reduce the risk of issues.
4. Encourage Developer Ownership: Encourage developers to write unit tests for their
code and track coverage as part of the development process. This increases
accountability and builds a robust codebase from the start.
5. Continuously Integrate Coverage Checks: Integrate code coverage tools into the
CI/CD pipeline to consistently monitor and enforce coverage standards with each code
change.
Benefits of Measuring Code Coverage
● A high percentage of software is less likely to contain defects resulting from
non-adherence to coding practices, overly complex code, or coding errors.
● A high percentage can imply that the code is more readable and maintainable.
● It helps provide stakeholders not involved in the software development process with a
way to gauge software quality.
● Since a larger team leads to ambiguity when defining well-tested code, this process acts
as an approximation metric, unifying the team's understanding of a well-tested code and
leading to a more consistent test practice.

Levels of Code Coverage
Method Coverage (Function Coverage)
Testers measure code through method or function coverage by counting the number of
functions a test suite calls.
Statement Coverage
Statements are instructions highlighting an action a program needs to carry out. Statement
coverage hence measures the percentage of code statements and gives an accurate estimate
of the quantity of code the tests execute.
Branch Coverage
Branch coverage measures whether a test suite executes the branches from decision points
written into the code. Such decision points arise from if and case statements, with two possible
outcomes: true and false.
Testers use branch coverage to verify if their test suite executes the branches from decision
points in the code. These are typically statements with two possible outcomes: a true and false
or an if and case statement.
The goal is to verify if the tests execute all branch points across a comprehensive set of inputs.
It helps testers measure code logic.
Condition Coverage
Developers use condition coverage to verify if tests execute statements using boolean
expressions in the code - this is another way of ensuring that tests perform all possible code
paths.
Multiple Condition Decision Coverage (MC/DC)
Each decision statement can have a combination of conditions. Multiple condition decision
coverage ensures that tests execute all these combinations seamlessly. Testers use this metric
to test safety-critical apps like those inside aircraft.
Parameter Value Coverage
As the name suggests, parameter coverage ensures that tests cover all possible parameter
values for each program. This metric is essential as neglecting specific parameter values leads
to software defects.

Cyclomatic Complexity
Testers use the cyclomatic complexity metric to measure the number of linearly dependent
paths in a program's source code. It is also helpful to determine coverage for particular code
modules.
Code Coverage Advantages
● You can use it to determine the quality and performance of any software.
● Code coverage helps maintain the code base.
● You can evaluate the quantitative measure of code coverage.
● It helps analyze the software verification process and access the test suite's quality.
● It exposes harmful and unused code.
● You can use it to create additional test cases.
● It increases time to market by increasing efficiency and productivity.
● It helps identify uncovered test cases.
● You can use it to measure test implementation efficiency.
Code Coverage Disadvantages
● It cannot always cover code entirely and accurately.
● You cannot test all feature values; it does not come with this guarantee.
What is Test Coverage?
Test coverage is a black-box testing technique that provides details on tests executed on an app
or website. Testers use it to ensure maximum coverage (according to the requirements outlined
in documents like FRS (Functional Requirements Specification), URS (User Requirement
Specification), and SRS (Software Requirements Specification), and to monitor executed tests.
How To Perform Test Coverage?
You can perform test coverage through various tests. However, the type of tests you run
depends on your testing team's business priorities. For example, an organization building a
user-centric web app will prioritize UI/UX tests over functional testing.
Here are some test coverage mechanisms, the scope could depend on definitions:
Functional Testing:
Functional testing involves testing app functionalities against client requirements or those
mentioned in the FRS documents.

Unit Testing:
Testers perform unit tests at the unit or module level. Bugs found at this level differ from those
found at the integration level.
Integration Testing:
Integration testing is also called system testing. Testers perform this test once developers
integrate all software modules.
Acceptance Testing:
You use this test to determine if a product qualifies for customer use. Typically, developers must
receive approval from SMEs and testers to push code changes from staging to production.
Testers use test coverage depending on the level at which they perform the tests and the type of
software they're testing. Moreover, test coverage metrics are different for mobiles and websites.
There are many times of test coverage and you can measure them at various testing levels like
component testing, integration testing, or acceptance testing.
Here are some coverage types:
Features Coverage
Features coverage involves writing test cases to help implement maximum coverage of product
features. These test cases must test all mandatory and optional features according to the
priorities set by the product team.
Risk Coverage
Risk coverage addresses the risks associated with the project. It helps mitigate these risks by
identifying the core issues. However, we cannot predict risks due to changes in market
conditions. Hence, we cannot use risk coverage at this stage.
Requirements Coverage
Requirements coverage ensures that when you write test cases, they provide maximum
coverage according to set requirements. Such a requirement can be the default language for an
SMS application - which is usually dependent on the location of where the app is released.
Types of Test Coverage

Test coverage evaluates how thoroughly the testing process examines the application's code
and functionalities. Key types include:
● Statement Coverage: Measures the percent of executable statements in the code
executed during testing. It ensures that each line of the source code has been tested at
least once.
● Branch Coverage: Ensures every branch in the control-flow graph has been executed.
For example, given an if statement, the true and false branches are tested.
● Condition Coverage: Verifies that each Boolean sub-expression has evaluated to be
both true and false. This ensures that all possible outcomes of each condition are tested.
● Path Coverage: Has every possible route through a given code been executed? This
ensures that all potential execution paths are tested.
● Function Coverage: Checks whether each function or subroutine in the program has
been called during testing.
Employing a combination of these coverage types helps identify untested parts of the code,
thereby enhancing the software's overall quality and reliability.
Code Coverage vs. Test Coverage: How to Choose?
While both code coverage and test coverage aim to improve software quality, they have a
different focus:
● Code Coverage: Measures the code executed during testing, providing a quantitative
assessment of test thoroughness. It helps identify untested parts of the codebase.
● Test Coverage: Assesses how well the testing validates that the application meets its
requirements and provides the desired user experience. It focuses on ensuring that all
functionalities are tested.
Choosing between them depends on your project's specific needs:
● Opt for code coverage to ensure that all parts of the code are executed, which is crucial
for identifying dead code and untested paths.
● Opt for test coverage when focusing on validating that all user requirements and
scenarios are thoroughly tested, ensuring the application behaves as expected.
In practice, combining both approaches provides a more comprehensive testing strategy,
balancing the depth of code execution with the breadth of functionality validation.
Disadvantages of Test Coverage
While test coverage is a valuable metric, it has its limitations:

● False Sense of Security: High test coverage percentages can be misleading, as they
don't guarantee the detection of all defects. Tests might execute code without verifying
correct behavior, leading to undetected issues.
● Quality of Tests: Test coverage measures the extent of testing but not the quality.
Poorly designed tests can achieve high coverage without effectively validating the
application.
● Resource Intensive: High test coverage can be time-consuming and may divert
resources from other critical testing activities, such as exploratory or usability testing.
● Maintenance Overhead: Extensive test suites require ongoing maintenance, especially
as the application evolves, to ensure they remain relevant and effective.
Recognizing these disadvantages is crucial for developing a balanced testing strategy that
maximizes test coverage's benefits while mitigating its drawbacks.
Test Coverage Best Practices
1. Define Clear Objectives: Locate what you aim to achieve with your tests, whether it’s
ensuring functionality, reliability, or performance. Set priorities based on critical
application areas.
2. Focus on High-Risk Areas: Concentrate testing efforts on modules that are prone to
defects or have been frequently modified. Critical functionalities and components that
directly impact user experience should receive higher coverage.
3. Optimize Test Cases: Avoid redundant tests and ensure each test case adds unique
value. Remove or update outdated test cases to keep the suite lean and relevant.
4. Regularly Review Coverage Metrics: Monitor and evaluate test coverage metrics to
align with project changes. Adjust coverage goals based on new feature additions,
changes, or refactoring.
5. Integrate Automation: Use automated testing tools to cover routine and repetitive
tasks, enabling faster feedback and maintaining high coverage with minimal manual
intervention.
Why Is Test Coverage Analysis Important?
Test coverage analysis ensures the identification of defects that you can address. Here’s why it
is essential:
Users Don't Tolerate Bugs.
A report from Statista highlighted that in 2019, 25% of users stopped using a mobile app after
just one use. Users will abandon an app that is glitchy or has many unexpected behaviors.
Running Various Tests Is Important

To ensure your app or website meets all requirements stated in the agile testing manifesto, you
must cover all testing types in your development process. You'll need to run performance,
security, functional, accessibility, and other tests to prevent defects. To ensure app
responsiveness and quality, you'll need to perform tests under real user conditions.
Developing and Implementing a Comprehensive Test Coverage Strategy
To ensure your test coverage strategy is effective, you need to ensure accuracy in:
● How you build and maintain your test labs.
● The platforms you include and use to test.
● Testing scenarios you build and execute for each software iteration.
HeadSpin: A Part of Your Test Coverage Tools
The HeadSpin Platform is a powerful test coverage solution that helps teams meet rigorous
quality standards across devices and environments. CloudTest Pro, our enterprise-grade
offering, provides access to dedicated real devices with support for functional testing and
performance KPIs, regression analysis, and continuous monitoring, making it ideal for teams
seeking comprehensive test coverage.
With CloudTest Pro, you can test and debug critical workflows on real SIM-enabled devices
under real user conditions, execute parallel tests on devices across 50+ global locations, and
integrate seamlessly with 60+ automation frameworks. The platform also enables cross-browser
and cross-device testing, ensuring comprehensive coverage across your application stack.
Advantages of Test Coverage
● It reports on portions of the codebase that necessary test cases have not covered.
● It helps detect areas of test cases that don't apply to a project. You can eliminate these
cases to make the code light.
● Developers can use it to create additional test cases when required to ensure maximum
test coverage.
● You can use it to prevent defect leakage.
Conclusion
Code coverage is an essential metric; however, test coverage is what you should aim to
achieve. By going beyond unit tests to acceptance tests, integration tests, and others, you
ensure your app is without glitches and is ready for production.
However, even with test coverage, ensure you develop a strategy as testing often without one
does not always result in good. Understanding your requirements and then testing is the best
approach you can take.

Article Source:
This article was originally published on:
https://www.headspin.io/blog/a-detailed-guide-to-code-coverage-and-test-coverage

Code Coverage vs Test Coverage_ A Complete Guide.pdf

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Code Coverage vs Test Coverage_ A Complete Guide.pdf