Measuring the quality of software is not always so cut and dry. Figuring out if an app is any good can seem a bit subjective and depends on who you ask and who the app is for. For all the opinions of what makes good software, however, the only things that really matter are how an app impacts your business’s bottom line.

Buggy code, after all, will drive users away and sloppy security measures could land you in serious hot water. A thorough check ensures your app will work as it’s supposed to work and keep your customers engaged.

As with anything in software development, it takes a process to do it right and it’s essential that you go through several stages of quality assurance. Why this matters is because you don’t want to release a shoddy product on the market. Software quality metrics set a standard for how to evaluate whether an app will be successful or not.

So can you really measure software quality? Of course, the answer is yes. This article discusses the different metrics in software testing, shows how we define software metrics, lists the goals of software quality assurance, and offers ways to improve software quality.

Development metrics

Software development metrics often keep three principles in mind: The number of lines of code per testing stage, the number of dependencies and dependency warnings, and the complexity of the code.

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How much code is tested at each stage?

There are four main stages in the software testing process. Each has its unique requirements which QA testers can measure different aspects of software quality. 

  • Unit test
  • Integration test
  • System test
  • Acceptance test

1. Unit test

Unit testing involves poring over an application’s code base line by line. This is a crucial stage in the testing process and is used to test each module separately from another module.

The developer is usually the one who tests the code at this stage, and this testing model determines which components of the code are doing what they’re supposed to do and which aren’t. The principle of the unit test is to isolate different portions of the code and test those portions to verify performance.

2. Integration test

Integration testing is more complex than the unit test phase and involves taking chunks of code and testing them together as a block. Testers perform this type of testing to see data flow across modules. Integration testing checks to see if the software is ready for the next phase, system testing.

3. System test

After a system has been successfully integrated, a system test is performed on it. This form of testing is more complex than the integration test stage and checks the system’s compliance under system requirements. The purpose of this is to evaluate both functional and non-functional needs for testing.

4. Acceptance test

An acceptance test is the final stage of testing before a system is ready to deploy. If the system test ensures that a system complies with the system requirements, then an acceptance test verifies that a system complies with the delivery requirements.

Dependencies and dependency warnings

To save time in the software development process, it’s tempting to rely on other people’s software instead of creating new code. While reusing other people’s software like packages and code libraries saves time, it can also leave you at the mercy of the original developer. Any changes made to the original code by its developer can lead to functionality issues in your code.

Of course, this means the dependent code is not as stable as original work, meaning that the more dependencies a code base has, the lower the quality. Decent developers and software providers will not try to cut corners and should definitely avoid dependencies in development.

Good code is well-protected against dependencies and dependency warnings. When the original code changes, poor code tends to start breaking down, while code designed according to data quality metrics remains functional in the long run.

Code complexity

Since one of the goals of software quality assurance is to ensure that code is stable, an important software quality metric is how complex or easily maintainable your code is. QA testers regard overly complex code with a poor structure, and inadequate comments as bad code. It’s harder to get a handle on complex code and can cost more to fix. It’s also less secure. Like code with a lot of dependencies, code that’s difficult to maintain long-term, is also poor-quality code.

One way to test code complexity is by using the Cyclomatic complexity structure. This measures the number of linearly independent channels a program’s source code runs.

There are dedicated toolsets for automated code review that measure the complexity and quality of a line of code:

While determining code complexity, the developer needs to perform a code review process. A code review process is the amount of time the developer waits before adding new code to an existing codebase.

Alternatively, CI/CD models can determine code quality.

Code Quality Metrics Using CI/CD

The CI/CD models can be used to set the requirements for code quality metrics in three ways:

1. Level of documentation

This measures the level of detail a project’s documentation has.

2. Increase in productivity you get using CI/CD

Productivity increases if you can achieve more deployments in less time and with less code freeze time. It also measures an increase in error detection.

3. Time constraints

This is a measure of how much time it takes to take ready and approved code to the production environment so that the client can see the changes. It also tracks how quickly the system can recover from application failure events, and whether there are lower failure rates per time.

Quality assurance metrics

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QA metrics are defined from the standpoint of a person whose priority is to ensure that the application development metrics do not go below a certain level of quality of the product/service. The three most important QA metrics in software testing are:

  • Requirements coverage metrics: the percentage of the aspects of software quality that have been covered by test cases.
  • The number of defects found per hour of testing: should decrease over time as testers find more bugs and send the code back to developers to fix.
  • The number of defects remaining open: these should also decrease over time, especially during the stabilization/release candidate period. This is largely dependent on how quickly developers can fix the bugs.

Business metrics

ROI and the bottom line are among the factors that inform software quality from a business standpoint. Business quality metrics fall into three central standards:

  • User experience
  • Customer satisfaction
  • Security threats

User experience

UX is one of the most important factors in evaluating software from a business perspective. Good UX improves user retention and drives more revenue into the service. Buggy code that has not gone through a proper QA review will drive customers away. Confusing navigation can increase errors and further infuriate users. Depending on the application, this can be unforgivable. Banking apps or others that deal with money have to have seamless UX and intuitive layouts.

Some UX factors in software quality metrics are:

  • The number of bugs reported by users within a given timeframe. Serious bugs should obviously decrease over time as you get closer to launch. After launch, there may still be minor bugs but the severity should be minimal. 
  • The number of users affected by bugs. Just as the overall number of bugs should decrease over time, so too should the number of users affected by the bugs. Quality software should be usable for the majority of users. 
  • Usability: how user-friendly the software is and the overall quality of the user experience. This can be evaluated using two methods:
    • A/B Testing
    • Checking that the software meets the functional requirements
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Customer satisfaction

Customer satisfaction should be one of the last metrics you use to evaluate a new piece of software, By the time an app is out in the world, it should have gone through several QA revisions. But software is notoriously complex and even the cleanest code can have bugs lurking. Giving your customers a chance to find bugs and report them is vital to maintaining a relevant and useful product.

This is measured by:

  • Customer feedback. End-users can evaluate how well the software meets their needs and solves the problems it’s supposed to solve.
  • How the software performs at scale. If a large number of people use the app, does it slow down or crash?
  • Several bugs that impact revenue stream, for example, how revenue is affected by bugs on a per quarter basis. The number of bugs is often tracked using severity metrics and this usually depends on what stage of development your product is in. Clients can report bugs or a metrics system can find them. This is the system that monitors revenue streams and reports spikes.

Security threats

A business-centric perspective on software quality metrics is also concerned with how secure the software is and how capable it is of keeping hackers out. Poorly tested or poorly maintained code can leave security holes hackers can exploit to steal personal data or funds.

Software that meets the software testing metrics and follows data quality metrics best practices should be able to check and ensure that all the employees registered on the system have correct access rights.

Check if your encryption methods are above or equal to recommended levels and are consistent across your organization as this is one of the goals of software quality assurance.

Why software quality metrics matter

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The need to define software quality metrics cannot be overstated. Code that cannot be evaluated accurately to test its efficiency, complexity and maintainability is not very good code. The need to track code quality by setting well-defined software quality metrics helps to determine the quality of your current system, improve its quality and accurately forecast what the quality of the system will be once the project is over.

The importance of software quality metrics is in their ability to measure software performance, plan work items and measure productivity. Having a set of objective measures gives you tools to decide whether a piece of software is worth the investment and can help you address areas for improvement. 

On a more granular level, software quality metrics help:

  • Identify necessary improvements
  • Optimize workload management
  • Minimize overtime
  • Reduce costs
  • Raise ROI

Managing software quality

Managing the quality of software involves developing the quality of software in a way that guarantees that the system meets end-users’ needs as well as regulatory standards. Software is in constant flux and so making sure your app remains useful, relevant and secure is a vital part of your strategy. Proper software quality management ensures quality assurance, quality planning, and quality control in a system. 

To do this well, you’ll need a solid team of QA testers to make sure your app meets these needs. The consequences for failing to properly test and maintain software quality can be severe. From legal battles to business losses, poorly maintained code that’s out in the world is a major liability. Work with a professional team to handle this complex process for you. You may also consider having a dedicated team who would make a top-notch product under minimal supervision.

Conclusion

When setting up a system or a product, it’s vital to pay attention to its quality at every stage of the application development life cycle. Because of the ambiguity of software quality, it’s up to you and your team how you choose to set up your own software quality metrics according to your goals and the needs you are trying to meet. Nonetheless, there are general templates you can follow to ensure that you stay on the right track when formulating your software quality metrics, and the steps above will guarantee that you do just that.

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Top 10 Software Quality Metrics that Matter - marcel-100px Hi, I’m Marcin, COO of Applandeo

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