Software Testing Basics: Types of Bugs Developers Need to Know

In order to understand the importance of software testing, let’s look into a scenario. You work hard on releasing the product within the deadline, too much time, energy and expenses have already been incurred in the cost of developing this software. When the moment of truth comes, you find out that the software is riddled with major and minor bugs. This results in negative reviews from the users because of unsatisfactory performance. This whole incident could've been avoided if software testing was done at the proper time in order to find out whether the software works as intended.

Any problems arising within the development phase should be fixed on high priority so that the final product is up to par. As humans, we are not above making mistakes. This is why software testing has always been an important part of the development process. There are certain bugs that are easy to get rid of and others are much more complicated. Here, let’s talk about the basics of software testing and the different types of bugs that developers should know in order to deal with this properly.

Identifying a Defect in Software Testing

For any quality product, there needs to be set of standards, which must be met before the product is released to the end-user. Being user-friendly is an important part of any software; however, defect-free is equally important. Software testing is the evaluation of a software application that a developer carries out in order to find any defects or errors that might compromise the quality. Software testing also checks for the specified requirements being met by the final product that helps in figuring out any shortcoming the software might have.

Software testing is also sometimes referred to as bugs testing which, as the name indicates is the testing carried out to find bugs in software. Developers often use the combination of manual testing and automated tools in order to conduct the software testing as effectively as possible. The performance of the software is tested with the expected requirements to identify possible gaps, errors or anything important missing from the actual requirements. After conducting software testing, the application will be reliable, secure and performing efficiently. These qualities can easily translate to a higher customer satisfaction rate, saving on excessive costs and time. Let’s look into some of the perks that come from software testing.

- Customer Satisfaction

Every software or product is developed with the goal of achieving a higher customer satisfaction rate. It is the single most important part of software product development. In order to ensure the best user experience, UI/UX testing is carried out.

- Cost Savings

If a bug is identified and fixed during the testing phase, the company doesn’t need to worry about the costs in the long term since it costs lesser to fix now than to fix in the future.

- Security of Software

Customers nowadays are most concerned about the security of the software they use and their privacy. Bugs testing also ensures that the software is secure enough for users.

- Product Quality

Software testing results in higher product quality since it removes all errors by the time software reaches the end-user.

Types of Software Bugs

Bug classifications are important to understand so that the developers know different types of bugs that can be found while software testing. Further, the QA process will also go smoothly once you can easily identify the type of bug you’re dealing with. In general, the types of bugs are classified under:

1. Classification by Nature

The types of defects that fall under classification by nature are far more than any other classification. When we talk about the nature of the bug, it is important to ask the right questions. Whether it’s low performance, weak security or sorting problems it can all be fixed if it is timely identified. Let’s see what different types of software bugs that fall under this classification.

Functionality Bug

A defect in software testing can be of functional nature, which means that the functions application is supposed to perform are not being performed. Developers can carry out functional testing that can help find bugs related to the software’s functionality. An example of functionability bug is having a option to sort in the software; however, the operation is not being performed.

Runtime Behavior Bug

This type of error appears in bugs testing when the program tries to carry out an operation, which is impossible to be finished. Imagine the program dividing a number by 0. Even though the example undermines the severity of the bug, it can actually result in software crash. However, there’s also a chance that the program will continue to attempt performing the operation without resulting in a crash.


Performance bugs are related to problems arising in consumption, stability of the software and latency issues. A defect in software testing is always compared with the set of requirements and the expected level of performance a software is supposed to perform at. The level of performance time taken for different functions in a software vary. Some tasks can stretch out much longer than others. Therefore, it is better to check the expected performance versus the actual performance of the specific function.


Usability bug is related to the ability of users understanding the basic functions of your software. If users are having a hard time figuring out the software and being able to perform tasks, this is classified under usability bugs.


Compatibility refers to the ability of a software to run on different hardware, OS or browsers. If the software performs inconsistently under these different platforms, it will be classified under compatibility issue.


Security is the heart of every software. Without proper security, customer’s data will be at risk of being exposed. Since it is also the biggest concern for customers, security bugs should be fixed right away as they can cause you to lose customers and expose you to unwanted liabilities.


Communication bugs compromise the end-user experience. The users should be communicated about the usage of software so it will be easier for them to find what they want and perform the actions that they want. Any new additions in the features of a software should be documented for the same purpose – better user experience.

2. Classification by Priority

Classification of bugs by priority is based on the importance of the bugs being fixed. If a bug crashes entire application, it will be classified as high-priority. Some bugs only have a minimal impact on the application itself, these will be classified as low-priority. The goals of your software will determine the priority of bugs to be fixed.

3. Classification by Testing Types


Syntax errors arise due to missing characters or some typing errors in programming. Syntax checker looks out for such bugs while the program is being executed.


A type-checker will find out whether your software is built with the affected program language, which enables static typing. Errors in function, coding, data type mismatch and bad logic fall under calculation errors.


This type of bug is a business logic-related error, which can be easily discovered through unit testing.

System-Level Integration

When software is developed, it has to work well with other modules as well. Integration tests can easily identify this type of bug.

Out of Bounds

Fuzzing tools allow developers to check for out of bound errors in the bugs testing. When users enter an integer in the place of a string, this bug can appear.

Control Flow

Control flow is the process that the software follows in terms of actions taken on certain conditions. When developers add new codes in a rush, control flow is sometimes affected. A cyclomatic complexity scanner can help in identifying control flow bugs.

Missing Command

Missing command bugs occur when the software is not equipped with a command that is expected. For example, if the software doesn’t have a close button, this is a missing command error.


Error handling bugs require user compliance. To help users solve the problem by themselves or forward it to technical support, a meaningful message is given that provides guidance. Background processes such as talking to a remote server or batch processing might face error-handling bugs.

Wrapping up

After learning different types of bugs, you can now easily access their importance when it comes to software testing. Prioritization of bugs is essential as it speeds up the process and improves the efficiency of testing and software development. The faster you finish software testing, the sooner your software can reach the end-user. Different characterization of bugs will help developers understand how much of an impact these bugs can have. Bugs occur too often in software/applications therefore, a proper streamlined process should be set in place for maximum efficiency. To err is human. Mistakes are a chance for learning so we can avoid similar errors in the future. Hope this article helps in clearing software bug testing-related concerns.

Share on:
Waleed Khan

19, Nov 2021

Waleed Khan is serving as the Director at APPSTIRR. An unapologetic serial entrepreneur, driven by the will to introduce unanticipated disruptive technology.

Next Article

How to Outsource Mobile App Development in 2022

Get in Touch

Get in touch with our experts

Looking for a brilliant app solution?

Get in touch with us


Copyright © 2021 Appstirr | All rights reserved.

Logo, portfolio, images and content are sole property of Appstirr (Labstirr LLC). All third party company names, brand names, trademarks displayed on this website are the property of their respective owners. Furthermore, Appstirr (Labstirr LLC) has no influence over the third party material that is being displayed on the website. Therefore, we are also not responsible for any resemblance with any other material on the web. These portfolios and case studies are actual but exemplary (for better understanding); the actual names, designs, functionality, content and stats/facts may differ from the actual apps that have been published. This is due to the strict NDA policy that Appstirr (Labstirr LLC) adheres to.