Defect Masking in Software Testing | What it is & Why it Matters?

September 25, 2023Lassya Krupa
Defect Masking in Software Testing What it is & Why it Matters

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When software is tested through several phases of software development, there are multiple issues that can occur. They can be functionality issues or a non-functionality one that the software engineers might need to debug. And, there could be some issues that may go unnoticed because of a lot of error clutter. This is what is the concept of defect masking. This phenomenon occurs when a significant software flaw could potentially lead to critical system failures. Therefore, effective testing strategies and thorough defect prioritization are crucial to mitigate this risk and ensure the identification of all critical defects during the testing phase.

What is defect masking?

Defect masking is a terminology in software testing that refers to a scenario where a critical defect goes undetected due to another defect or issue that attracts more attention during the testing process. Defect masking can be a serious concern as it may result in the release of faulty software, ultimately compromising system reliability and user satisfaction. 

Masked Defects Example

An example of a masked defect that is easily visible but unnoticed is a faulty user interface. Let’s say the UI that was built is extremely visually attractive but some of the most important functionalities according to the requirements of the application might not be easily visible which would impact the business revenue. 

Another example would be when integrating multiple software components or third-party libraries, integration issues may arise. These issues can sometimes mask defects within individual components. For instance, a defect in one module may only become apparent when integrated with others, making it harder to trace the root cause.

One of the most common examples is that a software product may function flawlessly in one environment but exhibit critical defects in another, like a production environment versus a development or testing environment. Testers might not discover these defects if they primarily focus on one environment and assume that the software is functioning correctly elsewhere.

Why Masked Defect?

Defects can become masked because of a combination of factors like limited resources, shifting priorities, and the complexity of software systems. When teams have constraints in resources and limited time, they often prioritize addressing more visible or urgent defects allowing less critical ones to remain hidden. 

This results in a scenario where the presence of defects is masked by other issues, becoming an unintentional byproduct of the software. These interdependencies often involve complex relationships between various components or modules within the software, making it challenging to predict how a defect in one area might affect or be obscured by defects in another. This phenomenon underscores the importance of meticulous testing, rigorous defect tracking, and comprehensive quality assurance practices to uncover and rectify all types of defects, especially those that could otherwise remain hidden and compromise the software’s integrity and functionality. 

In essence, defect masking is a nuanced challenge that requires vigilant attention to detail and effective testing strategies to mitigate its impact.

Practical description of masked errors

In practical terms, consider a scenario in which a software development team is working on an e-commerce platform. During testing, they discovered a minor formatting issue in the product description section that caused a huge misalignment in the text. This cosmetic issue is quickly identified and resolved because it’s readily available to testers. 

However, buried within the same codebase, there’s a more critical defect related to payment processing that occasionally results in incorrect transactions, but it’s rare and doesn’t consistently trigger errors. This severe payment bug remains unnoticed because the team’s attention is predominantly focused on fixing the visual flaw. 

So, the payment error remains masked by the less impactful formatting issue, posing a significant risk to the system’s financial integrity and user trust. This practical example illustrates how a less critical defect can mask a far more severe one when testing and development priorities are not effectively managed.

What is the difference between latent and masked defects?

There often is a misconception between masked and latent defects. So here are its differences.

Latent DefectsMasked Defects
Latent defects are defects within the software that are present but dormant or inactive. They do not manifest themselves until specific conditions or scenarios arise.Masked defects are defects that go unnoticed or undetected during testing due to the presence of other defects or because they are overshadowed by more visible issues.
Latent defects are triggered by specific and often uncommon usage patterns, data inputs, or environmental conditions that are not typically encountered during regular testing.Masked defects are concealed by other defects and may only become apparent when the masking defects are resolved, or under specific, often uncommon, circumstances.
Latent defects may remain dormant for an extended period and can potentially go undetected for a long time if the triggering conditions do not occur.Masked defects are usually detected only when the defects masking them are fixed or when the right set of conditions is met during testing or real-world usage.
A latent defect in a backup system might only become active and noticeable when a specific type of system failure occurs, triggering the backup process.A masked defect might occur when a critical software bug is concealed by the presence of other, less impactful issues, leading testers and developers to overlook it during testing.
Latent defects can have severe consequences when they become active, potentially leading to system failures, data loss, or other critical issues.Masked defects can impact software quality by allowing critical issues to go unnoticed, potentially leading to user dissatisfaction, financial losses, or compromised system reliability.

How can test automation help?

If you have test cases that need to be executed repeatedly, and you see test automation generating an ROI in the long run, it is always recommended to automate your tests.

Automating these tests ensures there is no masked defect in the areas where tests are automated.

To know more about mobile app testing with Testsigma read here: https://testsigma.com/automated-mobile-app-testing

To know more about automated web application testing with Testsigma read here: https://testsigma.com/automated-web-application-testing 


In conclusion, defect masking is a significant concern in software testing that can lead to the release of faulty software. Addressing this issue requires a combination of robust testing practices, effective communication, defect prioritization, and a commitment to delivering high-quality software to end-users.

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