Measuring software quality is an essential part of software development. It ensures that the software product is free from bugs, meets the required performance standards, is secure, and is user-friendly. However, to measure the quality of software, developers need to know what metrics to use.

In this article, we'll discuss the four essential categories of software quality metrics and when to measure them. We'll also cover how developers maintain software code quality and how the QA team measures software code quality.

The Four Essential Categories of Software Quality Metrics

Software quality metrics can be technical, but they can be boiled down into four essential categories. They are code quality, performance, security, and usability.

1. Code Quality

Code quality refers to bug-free and semantically correct code. Quantitative quality metrics measure the size and complexity of the software program, the number of lines and functions it contains, and how many bugs there are per 1,000 lines of code. Qualitative code quality metrics measure maintainability, readability, clarity, efficiency, and documentation. These metrics measure how easy the code is to read, understand, and whether it adheres to coding standards.

2. Performance

Performance metrics measure whether the software product fulfills its purpose and performs the way it is meant to. It also refers to how the application uses resources, its scalability, customer satisfaction, and response times.

3. Security

Software security metrics measure the inherent safety of a software program and ensure there are no unauthorized changes in the product when it is handed over to the client.

4. Usability

Usability refers to whether the software program is practicable and user-friendly. It is an important quality metric since all software products are built for end-users. We also ensure that the client is happy with the features and performance.

When to Measure Software Quality

Software development teams and Quality Assurance (QA) teams work together to ensure that the software quality is of the highest standard. The QA team does product testing once it is developed. However, the development team also maintains, measures, and constantly improves software quality during the build. We may test them at different points in development based on the development methodology used. We use two methodologies when developing software applications – Waterfall and Agile.

Measuring Software Quality: Waterfall Methodology

Waterfall methodology is when we plan, execute, test, and deliver in distinct phases. Each phase is completed before the next one begins. With a product developed using this methodology, we need to maintain the quality of the product at every stage – requirements, design, implementation, verification (or testing), and maintenance. Since testing is done at the end of the build, it takes less time and does not require much regression testing.

Measuring Software Quality: Agile Methodologies

Agile methodologies are more responsive and flexible, where the development is broken up into phases or sprints. The goal is that at the end of each sprint, which can be between two to six weeks long, we deliver a high-quality minimum viable product that is fully functional and tested. This means we have to make sure we maintain product software quality at each step, in each sprint. Products developed using Agile methodologies are tested more often. However, it also means that they need constant regression testing to ensure that an update hasn’t broken the functionalities that were tested and passed in earlier builds.

How Developers Maintain Software Code Quality

Developers measure their code quality as they develop, since it means they can identify and fix any problems during the build. They measure their code against coding standards, code reviews, code analyzers, and refactor legacy code. At this stage, software quality is tested manually with short unit tests. A unit test is the first stage of software quality measurement, where the smallest testable part of the software – a module or component of the program or even a single function within the code – is checked.

Developers create a shared library of hundreds of such tests, with repeatable functionality embedded in the software, so these tests can be used over and over again, across projects for efficiently detecting errors in the software code at the development stage. They also conduct automated testing using a code analyzer, SonarQube, which checks software for clarity, maintainability, documentation, extendibility, efficiency, well-tested, secure coding, code refactoring, and extendibility.

SonarQube

helps us conduct code reviews, maintain coding standards, identify bugs and the

number of potential bugs in the software. We also use it to assess the

structural complexity of the program (number of lines of code), any

vulnerabilities found in repositories, code smells (code that is confusing or

difficult to maintain), code coverage (measure of code covered by unit tests),

and code duplication (amount of code that is repeated).

How the QA Team Measures Software Code Quality

QA testers review all the metrics of software quality through manual and automated testing

(using Selenium), including the validity and standard of the product code.

Manual test metrics can be divided into two classes – Base metrics and

Calculated Metrics. Base metrics are made up of the raw, unanalyzed data that

is collected, while calculated metrics are derived from the information that was collected in the base metrics.

Manual Test

Metrics: Some of the important manual test metrics that we consider for software quality are test

case execution productivity metrics, test case preparation productivity

metrics, test duration, unit test coverage (the amount of software code that is covered by unit tests), and pass/fail percentage of tests, etc.

Automation

testing can help reduce the amount of manual time spent testing software

quality. Here are some of the important metrics for automation testing that we

consider: total test duration, unit test coverage, path coverage (how many

linearly independent paths of the program the test covers), requirements

coverage, pass/fail percentage of tests, number of defects, percentage of

automated test coverage (against the total test coverage, which includes manual

testing), test execution (total tests executed during the build), useful vs. irrelevant results, defects in production, percentage of broken builds, etc.

Other Types of Tests for Measuring Software Quality

We also use:

various types of tests 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 help

ensure that the software product is of high quality, meets the required performance standards, is secure, and is user-friendly.

Conclusion

Measuring software

Quality is an essential part of software development. It ensures that the

software product is free from bugs, meets the required performance standards,

is secure, and is user-friendly. Developers need to know what metrics to use to

measure software quality, and they need to maintain software code quality

during the build. The QA team plays a crucial role in measuring software code

quality through manual and automated testing. By measuring software quality, we

can ensure that the software product we deliver is of the highest standard and meets the client's requirements.