Defect Prevention Principles, Methods and Techniques

As with any form of creation, manufacturing, and development, it is better to identify problems sooner rather than later. Regarding software development and testing, this is exceptionally true. 

When it comes to pushing high-quality software, defect prevention is integral. Catching bugs and anomalies early makes it much easier to resolve them, as opposed to dealing with their effects once they have been enmeshed into the system. 

In this piece, we’ll dive into the definition, necessity, and principles of defect prevention.  We’ll also discuss techniques to perform defect prevention and the integral role of automation in this layer of quality assurance. 

What is Defect Prevention?

Defect prevention is a strategy in the SDLC that is deployed to identify and target the root causes of any defects. The process involves analyzing defects appearing in past projects, laying down distinct checkpoints in the pipelines, and taking action to prevent the emergence of similar defects/bugs/anomalies in the future. 

Defect Prevention is built on the extraction of and sharing of technical knowledge between QA teams or testing projects. Prevention methods are used to improve quality and productivity while keeping development costs low. 

Advantages of Early Defect Detection

• Defects are much easier to handle if discovered at an early stage. Rigorous detection cycles can identify potential issues before they snowball into bigger, more expensive problems. Think of it as examining the raw materials in a manufacturing process before sending them into the manufacturing pipeline.
  
• Reduces rework, waste and minimizes the risk of customer complaints and app uninstallations.
  
• Allows teams to monitor operations, analyze data, and narrow down testing areas for optimization and change. Leads to lower cycle times, higher efficiency rates, and targeted utilization of resources. This inevitably translates to cost savings.
  
• Frees up dev and QA time that would otherwise be spent dealing with completely avoidable bugs.
  
• Forces test leaders to think in terms of prevention and optimization when designing test cases, scripts, and implementation guidelines.
  
• Involves collaboration with all stakeholders so as to prioritize what defects and bugs should be quickly detected, based on user paths, preferences, actions and business needs. 

Principles of Defect Prevention 

Software Requirements Analysis

Defects in the requirements and design phase will translate to foundational source code, if not rooted out at the source. Requirements-based defects are the hardest to eliminate after coding begins, because it often means undoing protocols that prop up the whole system. 

These defects cannot be found via traditional testing methods. They require review and inspections after the documents are finalized. 

Read More: Techniques To Prevent Software Bugs

“According to Crosstalk, the Journal of Defense Software Engineering, “most failures in software products are due to errors in the requirements and design phases—as high as 64 percent of total defect costs.” Source

All software requirements and designs must be reviewed to ensure that the requirements accurately reflect customer needs. Consider running sessions between devs and customers so the software creators understand what they need to prioritize in their code. 

Reviews: Self-Review and Peer Review

Self-reviews and peer reviews refine code quality by bringing multiple pairs of eyes on the source code. These reviews are excellent for ferreting out algorithm implementations, holes in logic, and missing conditions. The self-review helps the developer clean up any obvious flaws they might have missed in a rush, while the peer reviews provide a new POV and the expertise of a fellow teammate or manager. 

Defect Logging and Documentation

All defects must be tracked, logged, investigated, and reported. Ideally, QAs should suggest structures/steps to resolve defects, but that usually only works out when the workload is not overwhelming (and it usually is). 

When considering the purchase of a defect tracking or defect management tool, check for the following features:

• Allows QAs to provide complete descriptions of each defect so that devs understand the problem in its entirety. 
• Allows QAs to clarify at which phase of software testing the defects have been encountered. 
• Allows QAs to upload screenshots/videos for further clarification.
• Contains space to mention the names of QAs who find each defect, so that they can be contacted by devs if so required. 

Root Cause Analysis and Preventive Measures Determination

Once defects are logged, they must be examined. Often a meeting (initiated by the project manager/coordinator) is required to explore root causes of as many defects as possible. 

This stage – defect analysis – aims to achieve the following: 

• Improving software quality by finding and neutralizing as many defects as possible, as early as possible. This requires examination of their root causes. 
• Understanding how the defect operates and what function it hinders by speaking directly to the QAs who found it.
• Diving into systemic errors whose cause is buried in the foundation structure of the source code. These bugs are the hardest to handle, and must necessarily be addressed at early stages of the SDLC.

Embedding Procedures into Software Development Process

Read More: Defect Removal Efficiency: How To Calculate It For Test Automation

The last stage of defect prevention requires teams to take their learnings from the analysis stage and use them to optimize the development process. It requires the entire team to figure out ways to modify existing processes, introduce new practices, and provide proof that these changes will have a tangible positive impact on final outcomes. 

A few tips to achieve the above:

• Provide monthly status reports of the team mentioning recurrent serious defects and analyses.
  
• Monthly (ideally) or fortnightly meetings to inform all stakeholders about the state of the SDLC and any major defects that choke its efficacy.
  
• Taking the time to regularly push for and implement better prevention measures into the SDLC (as far as stakeholder approval makes it possible).
  
• Monitoring the SDLC before and after implementation defect prevention tactics. Have they actually led to a reduction in the number of defects?

Role played by Test Automation in Defect Prevention

Traditionally, test automation has been used to identify defects and refine the QA process by taking human effort out of repetitive and time-intensive tasks. Instead of running a regression test manually for the 6th time, testers can focus on complex problems that machines cannot solve. 

Test automation plays the most integral role in defect prevention – finding defects quickly and easily. By creating suitable test scripts, QAs can automate predetermined user actions and analyze the actual results without having to run each step themselves. 

Take acceptance tests as an example. Teams can build a set of criteria that denote that software functioning is “acceptable” and deploy automation tools like Testsigma to follow the script and generate error-free results. 

Not only does test automation reduce the time and effort required to sniff out major and minor defects, it also takes human error out of the equations. Human eyes and minds are naturally prone to error, especially when they are looking at the same screen and performing the same action over hours. Machines, fed with appropriate and comprehensive input parameters, do not have the same problem. They do not get tired and they do not make human mistakes. 

Summary

Quality Assurance doesn’t just eliminate bugs as they show up. In its larger context, QA professionals envision and implement systems to better filter out defects that hamper software performance and user experience. 

As technology evolves, so do the defects that infect it. Defect prevention takes a step back from immediate debugging (though that is still very much a part of it) and applies testers’ real-world experiences to development and testing contexts. 

Defect prevention reduces testing costs, effort and time. It has a direct positive impact on the ROI of QA budgets, because it examines the cause rather than the symptoms of software malfunction. 

Frequently Asked Questions

What is a checklist and how does it prevent defects?

A checklist is used by QA engineers to note down all steps or tasks to be accomplished in a project. In the defect prevention ecosystem, checklists offer a systematic approach to everything that needs to be done to actually prevent defects. 

QAs refer to checklists to confirm that every user step and bug detection mechanism has been enacted or implemented. It is directly useful for improving efficiency, quality, and safety mechanisms. 

What is the difference between defect detection and defect prevention?

As the phrases themselves suggest, defect detection is confined to the act of identifying defects in the software as it is developed. Defect prevention, on the other hand, uses experience from past projects to create and embed practices that prevent too many defects from emerging in the first place. 

Defect detection is part of defect prevention, but not vice-versa. 

How does QA prevent defects?

The process of Quality Assurance (QA) focuses primarily on finding, tracking, analyzing, reporting, and eliminating defects in software. It also involves building systems to prevent defects from showing up too frequently by addressing the common root causes. By studying such causes, software behavior, and user expectations, experts can put appropriate filters to prevent defect leakage in place. They can also recommend best practices that minimize the likelihood of bugs emerging from errors in requirements, design blueprints, and rushed coding.