How to attain Maximum Test Coverage

Achieving 100% test coverage is often seen as the gold standard in software testing, though it remains a challenging goal. By combining systematic approaches with creative techniques, we can ensure that all critical aspects of the software are thoroughly validated, enhancing its reliability and quality, and making it more resilient and user-friendly. In this blog, let’s explore practical strategies to maximize test coverage.

Types of Test Coverage

 

Test coverage can be approached in various ways, each representing different aspects or dimensions of the testing process, focusing on specific goals. Below are some key concepts of test coverage in black box testing:

 

Requirement Coverage

 

Requirement Coverage ensures that all requirements in the Software Requirements Specifications (SRS) document are covered during testing. The SRS outlines the project’s business requirements as well as functional and non-functional requirements. In this type of coverage, every requirement in the SRS is mapped to one or more test cases. Testers verify that these test cases validate the functionality and acceptance criteria of each requirement.

A Requirement Traceability Matrix (RTM) is commonly used to map requirements to test cases and track completeness. This approach is most effective when testers have full access to all client-provided requirements.

To achieve this:

> Create an RTM to map each requirement to one or more test cases.

> Thoroughly review the SRS to identify all functional and non-functional requirements, and ensure that the test cases validate the acceptance criteria.

The formula for calculating Requirement Coverage is:

Requirement Coverage = (Number of Requirements Tested / Total Number of Requirements) * 100

 

Functional Coverage

 

Functional Coverage measures the extent to which all features and functionalities of the application have been tested to ensure the software performs as expected. It evaluates how thoroughly the application's behavior has been tested and is useful for identifying gaps in the testing of specific features or functions. This type of coverage is particularly applicable when testers do not have access to the SRS documents or when the application has undergone updates without proper documentation.

To achieve this:

> Ensure that test cases cover all functional scenarios derived from the application's intended behavior.

> Execute these test cases across all applicable features and compare the results against expected outcomes to identify any gaps.

The formula for calculating Functional Coverage is:

Functional Coverage = (Number of Functional Requirements Tested / Total Number of Functional Requirements) * 100

 

Compatibility Coverage

 

Compatibility coverage ensures that the application performs consistently across different operating systems, browsers, and devices. To validate uniform functionality and user experience across various platforms, the same test cases need to be executed on multiple platforms. This includes cross-browser testing and device compatibility testing to confirm the application’s consistency.

To achieve this:

> Create a test matrix of platforms and devices based on user demographics and compatibility requirements.

> Run predefined test cases on each platform combination, documenting results to validate consistent behavior across all environments.

The formula for calculating Compatibility Coverage is:

Compatibility Coverage = (Number of Successfully Tested Combinations / Total Number of Planned Combinations) * 100

> Number of Successfully Tested Combinations: Refers to combinations (e.g., browsers, operating systems, devices) that pass testing without significant issues.

> Total Number of Planned Combinations: Refers to the total set of combinations identified based on the target audience and compatibility requirements.

 

Strategies for Maximum Test Coverage

 

While achieving absolute 100% test coverage is theoretically ideal, the practical objective is to ensure that all critical aspects of the software's requirements and functionalities are thoroughly tested. 

By combining systematic approaches with best practices, it is possible to design effective tests and achieve test coverage that approaches 100%. Below are some of the key strategies to maximize test coverage effectively

 

Effective Test Design

 

Effective test design starts with a clear understanding of the requirements. This is achieved by thoroughly reviewing SRS, FRS documentations or User stories. After understanding requirements test cases should be written to comprehensively cover all functionalities. 

 

Test Case Strategies

 

When writing test cases, follow key strategies such as Happy Path Testing, Negative Testing, Boundary Value Analysis, and Decision Table Testing. These systematic approaches help ensure comprehensive test coverage.

 

Requirement Traceability Matrix (RTM)

 

Use Requirement Traceability Matrix (RTM) to verify all the requirements are covered in test cases. RTM maps each requirement to its corresponding test cases, ensuring that every functionality mentioned in the documentation is covered in test cases. It also helps identify extra test cases that may not be aligned with the user requirements.

There are three types of Requirements Traceability Matrix (RTM): Forward, Backward, and Bi-Directional. Choose the appropriate type based on the application's requirements. For more details about RTM, click here.

By using RTM and above mentioned case strategies we can write test cases systematically. To achieve further coverage, approach on-structured methods can provide a more holistic testing strategy. 

 

Risk Analysis 

 

Risk analysis involves identifying and evaluating potential risks that could impact an application's performance, functionality, and overall success. This process includes assessing the history of issues related to the system, project, or domain. By focusing on these potential risk areas, critical components can be tested thoroughly under real-world scenarios, ensuring a more robust and reliable application.

 

Error Guessing

 

This testing process relies on the tester’s domain knowledge, experience, and out of the box thinking capability. From the previous test results, common coding or design errors testers can predict the areas where the application might fail. 

 

Exploratory Testing

 

Exploratory Testing involves unscripted, flexible testing where testers use their intuition, experience, and creativity to uncover potential issues. It is especially effective when performed by testers with little prior knowledge of the application, as their fresh perspective often reveals unexpected issues. This technique is valuable for identifying risks, real-time vulnerabilities, user experience flaws, and edge cases that structured test cases might overlook.

 

Maintain Test Cases and Test Suites properly

 

Testing process is built upon well-structured test cases. When a defect is identified during testing and can be traced back to an associated test case, it signifies optimal coverage, ensuring that no issues are overlooked and defects are effectively detected within the scope of the designed test cases and test suites.

To ensure this level of sustained effectiveness, it is essential to write test cases with precision and maintain them diligently. As the application evolves, its features and requirements may change, meaning that the test cases must be reviewed, updated, and optimized regularly.

> For every new feature, write clear and concise test cases that are easy to understand. Ensure they cover all the possible ways that the feature might be used.

> Whenever there are modifications in the application, update the relevant test cases to ensure they are still valid and aligned with the new requirements.

> Test cases should be written based on the SRS or FRS documentation or Agile user stories. 

> When there is an update or removal of an existing feature use RTM to identify which test cases need to be modified or removed or which features need new test cases to align with the updated requirements.

> Remove any outdated or irrelevant test cases to keep the test suite lean, efficient, and relevant to the current application.

> Periodic reviews help ensure test cases remain aligned with the current application and cover all functionality of the application.

> Group related test cases together by module or business priority-wise to improve efficiency in running tests. This allows for better prioritization and management, especially when testing large applications with many features.

Proper maintenance of test cases and test suites ensures that the testing process remains aligned with updates to the application. This practice enhances the overall quality of the software by providing a clear reference for future testing cycles, ensuring that all functionalities are covered, and maximizing test coverage across all areas of the application.

 

Conclusion

 

Achieving 100% test coverage may sound not practically feasible but with the right testing techniques and strategies, it is possible to ensure all critical areas of the application are thoroughly tested. Testers with strong domain knowledge can design test cases that cover a broad range of scenarios, from common use cases to edge cases. Maximum test coverage allows teams to identify potential issues early, reducing the risk of defects and improving the stability of the application. It also boosts developer confidence and enhances overall product quality. In conclusion, comprehensive test coverage plays a vital role in ensuring the success of the software and long-term user satisfaction.