Measuring the quality of software is a crucial aspect of software development. It guarantees that the software product is devoid of errors, meets performance standards, is secure, and offers a user-friendly experience. However, developers must have knowledge of the metrics used to measure software quality.
In this article, we will explore the four primary categories of software quality metrics and when to apply them. We will also discuss how developers maintain code quality and how the QA team measures software quality.
The Four Fundamental Categories of Software Quality Metrics
Software quality metrics can be technical, but they can be simplified into four key categories: code quality, performance, security, and usability.
- Code Quality
Code quality refers to bug-free and semantically accurate code. Quantitative quality metrics measure various aspects such as the size and complexity of the software program, the number of lines and functions it contains, and the number of bugs per 1,000 lines of code. Qualitative code quality metrics evaluate maintainability, readability, clarity, efficiency, and documentation. These metrics indicate how easy it is to read and understand the code and whether it adheres to coding standards.
- Performance
Performance metrics determine whether the software product fulfills its intended purpose and performs as expected. It also considers resource usage, scalability, customer satisfaction, and response times.
- Security
Software security metrics assess the inherent safety of a software program and verify that no unauthorized changes occur when the product is handed over to the client.
- Usability
Usability refers to whether the software program is practical and user-friendly. This metric is crucial since all software products are designed for end-users. It also considers client satisfaction with the features and performance.
When to Measure Software Quality
Software development teams and Quality Assurance (QA) teams collaborate to ensure that the software meets the highest quality standards. The QA team performs product testing once it is developed. However, the development team continually maintains, measures, and improves software quality throughout the development process. The timing of measurement can vary depending on the development methodology used. Two common methodologies for software development are Waterfall and Agile.
Measuring Software Quality: Waterfall Methodology
In the Waterfall methodology, the development process is divided into distinct phases – planning, execution, testing, and delivery. Each phase is completed before the next one begins. With this methodology, it is important to ensure product quality at every stage – requirements, design, implementation, verification (or testing), and maintenance. Since testing is conducted at the end of the build, less time is required, and extensive regression testing is not necessary.
Measuring Software Quality: Agile Methodologies
Agile methodologies are more flexible and responsive, breaking the development process into phases or sprints. The goal is to deliver a fully functional and thoroughly tested high-quality minimum viable product at the end of each sprint, which can last between two to six weeks. This means that product software quality must be maintained in every step and sprint. Products developed using Agile methodologies undergo more frequent testing, but also require constant regression testing to ensure that updates do not break previously tested and approved functionalities.
How Developers Maintain Software Code Quality
Developers continuously measure their code quality as they write code, allowing them to identify and resolve issues during the development process. They assess their code against coding standards, engage in code reviews, use code analyzers, and refactor legacy code. At this stage, software quality is tested through short unit tests. A unit test evaluates the smallest testable part of the software, such as a module, component, or even a single function within the code.
Developers create a library of hundreds of these tests, containing repeatable functionalities embedded in the software. These tests can be reused across projects to efficiently detect errors in the software code during the development stage. Additionally, automated testing is performed using a code analyzer tool like SonarQube. SonarQube checks the software for clarity, maintainability, documentation, extendibility, efficiency, secure coding, code refactoring, and extendibility.
SonarQube helps facilitate code reviews, maintain coding standards, identify bugs, and quantify potential bugs in the software. It assesses the structural complexity of the program (number of lines of code), identifies vulnerabilities in repositories, detects code smells (confusing or difficult-to-maintain code), measures code coverage (extent of code covered by unit tests), and identifies code duplication (repeated code).
How the QA Team Measures Software Code Quality
QA testers review all software quality metrics through manual and automated testing, including evaluating the quality and standards of the product code.
The manual test metrics can be categorized into two classes – Base metrics and Calculated metrics. Base metrics consist of raw, unanalyzed data collected during testing, while calculated metrics are derived from the data collected in the base metrics.
Manual Test Metrics: Some important manual test metrics for measuring software quality include test case execution productivity metrics, test case preparation productivity metrics, test duration, unit test coverage, and the pass/fail percentage of tests.
Automation testing can help reduce the manual effort required for testing software quality. Key metrics for automation testing include total test duration, unit test coverage, path coverage, requirements coverage, pass/fail percentage of tests, number of defects, percentage of automated test coverage, test execution, useful vs. irrelevant results, defects in production, and percentage of broken builds.
Other Types of Tests for Measuring Software Quality
Various types of tests are employed to measure software quality, including functional testing, test to break, load performance testing, regression testing, security testing, penetration testing, and user acceptance testing. These tests ensure that the software product is of high quality, meets performance standards, is secure, and provides a user-friendly experience.
Conclusion
Measuring software quality is a critical aspect of software development that ensures the delivery of a high-quality software product that meets performance standards, is free from errors, is secure, and offers a user-friendly experience. Developers must be familiar with the appropriate metrics for measuring software quality and must maintain code quality throughout the development process. The QA team plays a crucial role in measuring software code quality through manual and automated testing. By prioritizing software quality measurement, we can be confident that the software product we deliver meets the highest standards and satisfies client requirements.
