16 Types of Bugs in Software Testing

Developers spend innumerable hours in software testing to find out bugs that could eventually degrade the software quality. Sometimes these bugs can be as simple as an unresponsive button whereas they can become highly severe where bugs could make the entire software unresponsive. In both ways, it is the user experience that will be affected and would lead to monetary losses of the organization. Considering that fact, software testing has become an integral part of every SDLC. This article will explain types of bugs in software testing.

What is a Software Bug?

While writing a software code, the developer could make a mistake that could hamper the functioning of a certain feature in the software. This mistake or error is the bug that will cause the software to malfunction. The reason why such errors are called a bug is because of an issue faced by Grace Murray Hopper, a renowned personality in computing history.

While working on an electromechanical computer, he faced an issue that affected the performance of the computer. While looking for the issue, he found a moth stuck inside the computer. Since then, every error in the software code or a computer system is called a bug.

Different Types of Bugs in Software Testing:

No matter the software type, software bugs are categorized into three types; Nature, Priority, and Severity. Classification of bugs in software testing is done on the basis of their nature and impact on the user experience.

• Software Bugs by Nature:
  Software bugs have different natures where they affect the overall functioning of the software differently. Though there are dozens of such bugs existing currently, you may not face them frequently. With that in mind, here are the most common software bugs categorized by nature that you are most likely to witness at some point in your software development career.
  
  1. Performance Bugs:
     No user wants to use software with poor performance. Software bugs that lead to degraded speed, stability, increased response time, and higher resource consumption are considered performance bugs. The most significant sign of any such bug in software is by noticing slower loading speed than usual or analyzing the response time. If any such sign is found, the developer may begin diagnosing a performance bug. The performance testing phase is part of the development process where every such bug is detected in the software.
     
  2. Security Bugs:
     While using software, security is the biggest concern of a user. Software with poor security will not only put the user's data at risk but will also damage the overall image of the organization which may take years to recuperate. Due to their high severity, security bugs are considered among the most sensitive bugs of all types. Though it is self-explanatory, security bugs may make the software vulnerable to potential cyber threats.
     
     Sometimes, the software organization may not notice such attacks whereas in some cases, these attacks could cause monetary loss to the users, especially small and medium-scale businesses. XSS vulnerabilities, logical errors, and encryption errors are some of the commonest security bugs found in the software. Developers put special focus on checking the code to find any underlying security bug to minimize the risk of cyber-attacks.
     
  3. Unit Level Bugs:
     Unit level bugs are fairly common in software development and do not cause much damage to it as well. Facing basic logic bugs or calculation errors are considered unit-level bugs. The testing team along with the agile team test a small part of the code as a whole.
     
     The reason why this testing method is preferred is to make sure that the entire code is working as it is meant to. While testing, the team may encounter unit-level bugs which can be fixed easily as the team is only working with a small code.
     
  4. Functional Bugs:
     Software is as good as the feature it provides. If any of the functionality of a software is compromised, the number of users will start to decline drastically until it becomes functional again. A functional bug is when a certain feature or the entire software is not functioning properly due to an error. The severity of such bugs depends on the feature they are hampering.
     
     For instance, an unresponsive clickable button that is not functioning is not as severe as the entire software not working. Functional testing is done by the testing team to identify any such software bug causing functionality errors. Once identified, the team decides its further classification and severity.
     
  5. Usability Bugs:
     Probably one of the most catastrophic bugs for software, a usability bug or defect can stop the software from working to its potential or make it entirely unusable. Examples of this bug in software testing are the inability to log in to the user account or the inefficient layout of the software for the user.
     
     The bottom line is that this type of defect or bug can make it complex for the user to use the software efficiently. The developers and engineers have to look out for the right usability requirements while testing the code to identify such bugs.
     
  6. Syntax Errors:
     Syntax errors are among the commonest software bug types and do not allow the application to be compiled appropriately. This bug occurs due to an incorrect or missing character from the source code due to which the compiling will be affected.
     
     A small error like a missing bracket could lead to this problem. The development or testing team will get to know about this bug during compiling and will further analyze the source code to fix the missing or wrong characters.
     
  7. Compatibility Errors:
     Whenever a software or an application is not compatible with hardware, or an operating system, it is considered as incompatible software or a compatibility error. Finding a compatibility error is not a common practice as they may not show up in the initial testing.
     
     Due to this reason, the developers should go for compatibility testing to make sure that their created software is compatible with common hardware and operating systems.
     
  8. Logic Bugs:
     Another one of the most frequently found bugs in a software code, logic errors make the software give wrong output, software crash or failure. In the majority of cases, these bugs are caused due to coding errors where it may make the software stuck in a never-ending loading loop. In that case, only an external interruption or software crashing are the two only things that can break the loading loop.
• Priority-Based Software Bugs:
  The foremost category here is priority-based software bugs. These are based on the impact these bugs leave on the business. Here, the developers will analyze the bug to determine its impact and its defect priority. Afterward, the timeline is given to each bug where it should be rectified within the stipulated time frame to minimize the bug effect on the user. Here are the four types of priority-based software bugs.
  1. Low-priority defects:
     Low priority defects do not cause much impact on the functioning of the application. Rather, they are more about software aesthetics. For instance, any issue with the spelling or the alignment of a button or text could be a low-priority defect. The software testing will move to the exit criteria even if the low-priority defects are not fixed, but they should be rectified before the final release of the software.
  2. Medium-priority defects:
     Akin to low-priority defects, medium-priority defects do not cause any significant impact on the software, but they should be fixed in any subsequent or upcoming release. Such defects may not have the same effect for every user and it may vary with the device as well as specific configuration they have.
  3. High-priority defects:
     Unlike the previous two, the exit criteria of high-priority defects are not met until the issue is resolved. Every bug falling in this category may make certain features of the software unusable. Even though it may not affect every user, it is mandatory to fix these bugs before any further step is taken in software development or testing.
  4. Urgent Defects:
     As the name suggests, all bugs that should be dealt with utmost urgency fall under this category. Urgent defects may leave a lasting impact on the brand image as well as affect the user experience drastically. The stipulated timeline for fixing these bugs is within 24-hours of reporting.
• Software Bugs by Severity:
  Depending on the technical effect that the bug will cause on the software, the bugs are categorized into four categories.
  1. Low Severity Bugs:
     Low severity bugs do not cause much damage to the functioning of the software as their primary target is the user interface. For instance, the font of the text on the program differs from what was used. These bugs can be fixed easily and are nothing to worry about.
  2. Medium Severity Bugs:
     Every bug that can affect the functionality of the software a little bit is considered a medium severity bug. All such bugs make the software function different from what it is supposed to function. Though they are not also major for the program, they should be fixed for a better user experience.
  3. High Severity Bugs:
     High severity bugs affect the software functionality, making it behave differently from what it was programmed for. Not only are such bugs damaging for the software, they sometimes make the entire software unusable for the user.
  4. Critical Bugs:
     Critical bugs are the most damaging bugs in the category that can hinder the functionality of the entire software. The reason why critical bugs are considered the most damaging is that further testing on the software becomes impossible till such bugs exist in the software.

Common Examples of Software Bugs

It's crucial to note that software testing plays a great role in resolving a lot of the above mentioned bugs.Here are some examples of each type of bugs in software testing. 

1. Syntax Errors: These mistakes might make the program act unexpectedly and prevent it from compiling. One such example is provided here to help you comprehend this error type better. Because there is no bracket at the end of the closing statement in this case, the code cannot be executed.  The closing bracket will be added to fix the same, as shown in the following figure.
   
   Int x = 10;
   If (x == 10)
   {
   Cout << 'x is equal to 10';
   }
   Else
   {
   Cout << 'x is not equal to 10';
   
   Because there is no bracket at the end of the closing statement in this case, the code cannot be executed.  The closing bracket will be added to fix the same, as shown in the following figure.
   
   Int x = 10;
   If (x == 10) {
   Cout << 'x is equal to 10';
   }
   Else {
   Cout << 'x is not equal to 10';
   }
2. Logic Errors:These mistakes may cause the program to provide an incorrect or unexpected result. It is analogous to ordering coffee when one wants green tea in real life. To illustrate, let us take a case where:
   
   a = 100
   while a < 10;
   a = a + 1
   print a
   
   The code looks clean, but the loop would not be executed as the initial value of a is 100. 
3. Runtime Errors: As the code is being created, these errors must be rectified to prevent program crashes. As an example, a program that computes the average of a list of numbers is being tested. Let's say this program hits a divide-by-zero mistake or has a boundary-related issue that prevents it from including an element that should have been included. The program will result in a runtime error in these circumstances. 
4. Memory Errors: These mistakes occur when a program tries to access a portion of the computer's memory that it is not meant to. Sensitive information may leak as a result of these mistakes. Memory issues are well illustrated by the 'buffer overflow error'. For instance, the program tries to write data to a temporary storage buffer that cannot accept it. If this condition is not handled carefully, it might result in a program overwriting in the nearby memory, which could cause unpredictable behavior. Developers employ bounds checking, input validation, and ongoing code review to eliminate these problems. 
5. Input Validation Errors: When a user enters data incompatible with the system, errors like these occur. For instance, one form has a field for age. Age must fall within the range of 10 and 20 years, and only numeric numbers may be submitted, according to the requirements provided by the system. Users will get an input validation error if they type 'fourteen' or '21.'  
6. Boundary-Related Errors: These mistakes occur when the system is not built to handle values at the boundaries that have been created's outer bounds. For instance, a program estimates the average attendance (over five years) for workers who make between $50,000 and $100,000 per month. Because the program can only accept numbers of 50,000, if any employee earns $50,000, the system may be unable to compute the same. Similar to the previous example, if an employee earns $100,000, the system cannot determine their attendance since it can not handle values exceeding that amount.
7. Calculation-Related Errors: These mistakes occur when the system is not built to handle values at the boundaries that have been created's outer bounds. For instance, a program estimates the average attendance (over five years) for workers who make between $50,000 and $100,000 per month. Because the program can only accept numbers of 50,000, if any employee earns $50,000, the system may be unable to compute the same. Similar to the previous example, if an employee earns $100,000, the system cannot determine their attendance since it can not handle values exceeding that amount. 
8. Calculation-Related Errors: This problem can occasionally be caused by the program using incorrect mathematical formulae. The most frequent causes of these problems are, among others, the employment of inappropriate algorithms, erroneous number rounding, and data overflow or underflow. Assume that while testing a banking application, the interest calculation formula is used: Interest = principal * (rate/100) * time. 
   Say, for example, 200 is being reported as interest in this situation while 205 should be the correct amount. The system may be rounding off the amount to the closest dollar, which might be the source of this. A calculation-related error is what we refer to as such an error. 
9. Compatibility Errors: For example, an Excel sheet or a certain program. This program's features won't be the same as those in its earlier and more current versions. Information (files) stored in the latest version may behave differently when opened in previous versions. This is how compatibility problems appear. A program is made available that is only compatible with Windows 10. A user may encounter compatibility issues while attempting to use the same program on any other version of Windows. 
10. Performance errors: These mistakes occur when the program doesn't work as it should. To help clarify this issue, one such example is provided below. A web application is designed to support 10,000 active users simultaneously without experiencing performance issues. Testing indicated that the program slows down once 7000 users have used it concurrently. The expectation of 10,000 users is not fulfilled in this case, and a performance issue is considered to have occurred. Testing experts go out of their way to identify and fix these problems. 

Impact of Software Bugs Examples:

Bugs in their system or the processes they are managing do not sit well with developers or testers. With their existence, the program's performance is hampered in several ways. If defects interfere with a product or application's proper operation or usefulness, the release date may be delayed. It's crucial to remember that performance flaws might be hard to find since they blend in smoothly.

Developers frequently improve their capacity for logical thinking and employ cutting-edge techniques for spotting these nefarious offenders while including end-to-end software testing. Some of the cases listed below explain how bugs impact the software in the real world. 

• In November 2021, Apple released a software update to fix a critical vulnerability allowing hackers to control users' devices. The bug affected Apple's macOS and iOS operating systems and could have allowed hackers to install malware, steal sensitive data, and more.
• In October 2021, a software bug caused a significant outage on Facebook, Instagram, and WhatsApp. The bug affected how the platforms route traffic between servers, making users unable to access or use the services for several hours.
• In September 2021, Microsoft released an emergency patch to fix a critical vulnerability in its Windows operating system. The bug, known as 'PrintNightmare,' allowed hackers to take control of users' computers and steal sensitive data.

How to Find Underlying Software Bugs?

Finding a software bug is a daunting task that should be done to ensure that the software functions as it should. However, the question is how to find software bugs. To help developers in accomplishing that task, here are some of the ways to find bugs in software.

• Use Test Cases:
  Test cases are among the foremost things that will help a developer in identifying bugs in the software. Every developer should prepare excellent test cases prior to their testing including functional test cases that will help them in analyzing the risk of the application and how it will perform under different circumstances.
• Test on Devices:
  Sometimes all developers do is test the code in a virtual machine, leaving behind real devices. In some cases, that approach may work, but this practice is ineffective in large-scale software. With that in mind, developers should expand their testing reach and test the software on multiple real devices. Doing so will not only help them in understanding how the software performs on different configurations, but will also help you in knowing its compatibility as well.
• Use Bug Tracking Tools:
  Bug tracking tools are probably the easiest way to identify bugs in software. Such tools aid in tracking, reporting, and assigning bugs in software development, making testing easier. Several such tools like SpiraTeam, Userback, and ClickUp are available that can accomplish this task and make software testing uncomplicated to much extent.

Bug Prevention and Resolution

Software testers aware of the software's potential faults may more effectively fix them. A deeper awareness of them can aid in locating each bug's residence and, consequently, getting rid of it. Some of the best practices for preventing logic, runtime, and syntax errors in software development are mentioned below.

• Considering the edge situations when the program is being built might help find faults in the original product. Edge cases are hypothetical situations that show what may go wrong in a specific circumstance. TDD can be effective in this scenario. 
• Additionally, having diverse testing environments is effective in preventing issues. A local development environment, a testing environment for developer testing, a staging environment for client testing, and a production environment for going live are all examples of environments. This encourages more failures before the product enters the staging and production environments.  
• Bugs in the software development process are significantly reduced through software testing. This might use shift left testing techniques or test-driven development. 
• Another effective strategy for addressing software vulnerabilities is to set up a notification system. In this case, sophisticated technologies like Jira, SmartSheets, and BugHerd might be helpful. 
• Establishing explicit accountability for who should repair bugs, when bugs should be addressed (the timeframe), and who handles these issues on the weekends or late at night is important. 
• If a bug is discovered in a production setting, it is advisable to put off addressing it there unless it is significantly impacting profits. Before being merged into production, bugs should undergo testing in the staging environment. 
• To determine what caused the issue, a detailed investigation is required. Understanding what can go wrong in the future and how such problems might be avoided is helpful in bug prevention. 

How to Identify and Resolve Bugs?

Keeping customers by fixing bugs before they notice them can be more effective. Finding and fixing bugs in live applications cannot be overstated because they pose a severe risk to the company's operations. Some of the suggestions above can help prevent issues, but it is crucial to find and fix them once they have happened. The methods listed in the points below offer some solutions for this.  

• Having proactive teammates who work backwards might help find software flaws. In this situation, it's crucial to concentrate on elements like configuration, code base, concurrency, logs, and backup services. 
• The purpose of implementing feature flippers is to improve application scrutiny. In the event of a problem, it enables the handlers to disable one or more functionalities that are available to the users. 
• Applying the chaotic engineering method while creating software to identify issues in diverse microservices environments is advised. It aids in deliberately breaking the product so that its behaviour, flaws, and other problems inside its system are discovered.

What's the Role of Testing in Software Development?

A significant portion of software development is software testing. This procedure involves determining if software or a product works as expected. Software testing's primary goals include inspecting the product and the documentation to determine whether the requirements or specifications are being met, finding defects, assessing quality and risk, fostering trust, and preventing problems. Bug prevention, decreased development costs, and improved performance are just a few benefits of testing. 

Importance of Testing in the Software Development Process

• It has been observed worldwide that customers need to respond better to untested applications and then launch them onto the market. It will inevitably return to the needs of the end user. Testing aids in finding and fixing faults and flaws, improving functionality and performance. 
• Customers lose interest in the website or program if it is buggy. Testing assists in launching high-quality items onto the market, keeping corporate reputation. 
• Trust in the hearts of the client is established. When consumers have more faith in the product, sales grow. As a result, the company's revenue rises. The primary driver behind this is a thoroughly tested application or final product. 

What are Types of Testing?

One may use a variety of software testing approaches to make sure that modifications to your code function as planned. However, not all testing is created equal or delivers similar results. One can examine how various testing methodologies vary in three popular ways.

• Unit Testing: Unit-level challenges, the most frequent errors, are flaws found in small code sections. These are the easiest to remedy, yet they are frequently missed throughout the coding phases. Unit testing makes it simpler to see errors as it takes up smaller parts of code and replicates them faster. It is regarded as the very first testing level and the starting point for subsequent levels of testing for these reasons. Additionally, catching a problem early will save money in the long run.

• Integration Testing: Unit testing is followed by integration testing, which tests the smallest possible set of units. Fixing the problems in certain units, this helps to improve their functionality. During this stage, automated tests are developed and run to make sure the program still functions properly after changes have been made to it. 

• User Acceptance Testing: This testing is carried out close to the end of the software development life cycle, following unit testing and integration testing. It entails testing the program in scenarios modelled after real-world ones to see whether it satisfies end-user requirements. Users may not discover some issues until after the platform launch if adequate UAT is not conducted. Returning to fix bugs and upgrade the platform will be more expensive and may harm the platform's reputation. 

Conclusion:

100 % eradicating bugs from software is practically inevitable. With every new update release or new software, some bugs will come along. Rather than looking for every bug and fixing it, developers and testers analyze the severity of the bug and determine whether fixing the bug is worth the effort or not. ThinkSys Inc performs rigorous software testing to find complex bugs in software. Furthermore, our software testers create a strategy to prioritize bugs that will help in making the software better with each update. The motive is to identify errors in an early stage so that the software can reach the release date quickly and error-free.

Reap the Benefits of ThinkSys QA Consulting

With that in mind, if you believe that you need professional consultation regarding software testing, you can always reach out to our QA Experts.

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