Software Defects can be found in every stage of product development and testing. In order to ensure that the most critical software defects are fixed, it is important for testers to have a good understanding of the different types of defects that can occur.
In this article, we will discuss the most common types of software defects and how to identify them.
What is a Defect?
A software defect is an error, flaw, failure, or fault in a computer program that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. A software bug occurs when the actual results don’t match with the expected results. Developers and programmers sometimes make mistakes which create bugs called defects. Most bugs come from mistakes that developers or programmer make.
Types Of Software Errors in Software Testing
There are many different types of software defects, and it is important for testers to be aware of the most common ones so that they can effectively test for them.
Software bugs are classified into three types:
- Software Defects by its Nature
- Software Defects by its Priority
- Software Defects by its Severity
Usually we can see the classifiers priority and severity in most of the bug tracking tools. If we setup a classifier according to their nature of bug along with priority and severity then it helps manage the assignment of bug fixing responsibilities to appropriate teams easily.
#1. Software Defects by its Nature
Software bugs have a wide range of natures, each with its own set of symptoms. Despite the fact that there are many such bugs, you may not encounter them often. Here are the most prevalent software bugs classified by nature, the ones you’re most likely to come across in software testing.
#1. Functional Bugs
As the name suggests, functional bugs are those which cause the software to malfunction. A good example of this would be a button which, when clicked, is supposed to open a new window – but instead, nothing happens. Functional bugs can be fixed by performing functional testing.
#2. Unit Level Bugs
Unit level bugs are defects that are related to the functionality of a single software unit. A software unit is the smallest testable part of an application. Examples of software units include classes, methods, and procedures. Unit level bugs can have a significant impact on the overall quality of the software.
Unit level bugs can be fixed by performing Unit testing.
#3. Integration Level Bugs
Integration level bugs are defects that occur when two or more software units are combined. These defects can be difficult to find and fix because they often require coordination between multiple teams. However, they can have a significant impact on the overall quality of the software.
Integration bugs can be fixed by performing integration testing.
#4. Usability defects
Usability bugs are defects that impact the user experience of the software that makes it difficult to use. A usability defect is a defect in the user experience of software that makes it difficult to use. Usability bugs are the bugs such as If a website is complicated to access or get around or the signup process is complicated to go through.
During usability testing, software testers check apps against user requirements and Web Content Accessibility Guidelines (WCAG) to look for such problems. However, they can have a significant impact on the overall quality of the software.
Usability bugs can be fixed by performing usability testing.
#5. Performance defects
Performance bugs are defects that impact the performance of the software. This can include things like the speed of the software, how much memory it uses, or how many resources it consumes. Performance level bugs can be difficult to track down and fix, because they can be caused by a number of different factors.
Usability bugs can be fixed by performing Performance testing.
#6. Security defects
Security bugs are a type of software defect that can have major consequences if left unaddressed. These defects can allow malicious users to gain access to sensitive data or systems, or even allow them to take control of the affected software. As such, it is critical that security level bugs are given high priority and addressed as soon as possible.
Security bugs can be fixed by performing Security testing.
#7. Compatibility defects
Compatibility defects are those bugs which occur when an application is not compatible with the hardware it is running on, or with other software it needs to interact with. Incompatibility between software and hardware can result in crashes, data loss, and other unpredictable behavior. Testers need to be aware of compatibility issues and test accordingly. A software application that has compatibility issues does not run consistently on different sorts of hardware, operating systems, web browsers, and devices when connected with certain programs or running under specific network conditions.
Compatibility bugs can be fixed by performing Compatibility testing.
#8. Syntax Errors
Syntax errors are the most basic type of defect. They occur when the code violates the rules of the programming language. For example, using incorrect punctuation or forgetting to close a bracket can cause a syntax error. Syntax errors will usually prevent the code from running at all, so they’re relatively easy to spot and fix.
#9. Logic errors
Logic bugs are defects that cause a program to produce incorrect results. These bugs can be difficult to find and fix because they often don’t produce any visible errors. Logic bugs can occur in any type of software, but they’re especially common in applications that require complex calculations or decision-making.
Common symptoms of logic bugs include:
- Incorrect results or outputs
- Unexpected behavior
- Software crashing or freezing
To find and fix logic bugs, testers need to have a strong understanding of the program’s code and how it should be working. Often, the best way to find these kinds of bugs is to use debugging tools or step-by-step execution to track the program’s execution and see where things go wrong.
#2. Software Defects by its Severity
A severity level is assigned to a defect by its impact. As a result, the severity of an issue reflects how much of an impact it has on a software product’s functionality or operation. Severity defects are classified as critical, major, medium, minor based on its severity measure.
#1. Critical Defects
A critical defect is a software bug that has a severe or catastrophic consequence on the operation of the application. Critical defects can cause the application to crash, freeze, or perform incorrectly. They can also result in data loss or security vulnerabilities. Critical defects are often given the highest priority by developers and testers because they need to be fixed as soon as possible.
#2. Major Defects
A major defect is a software bug that has a significant consequence on the operation of the application. Major defects can cause the application to perform slow or exhibit other unexpected behaviours. They can also result in data loss or security vulnerabilities. Major defects are often given a high priority by developers and testers because they need to be fixed as soon as possible.
#3. Minor Defects
A minor defect is a software bug that has a small or insignificant consequence on the operation of the application. Minor defects can cause the application to perform slightly slow or exhibit other unexpected behaviours. Minor defects are often given a low priority by developers and testers because they can be fixed at a later time.
#4. Trivial Defects
A trivial defect is a software bug that has no consequence on the operation of the application. Trivial defects can cause the application to display an error message or exhibit other unexpected behaviours. Trivial defects are often given the lowest priority by developers and testers because they can be fixed at a later time.
#3. Software Defects by its Priority
#1. Low Priority Defects
Low priority defects are generally the ones which do not have any serious impact on the functioning of the software and can be deferred to be fixed in the next version or release. Cosmetics errors like spelling mistakes, incorrect alignment, etc. come under this category.
#2. Medium Priority Defects
Medium priority defects are the errors that may be fixed after an upcoming release or in the subsequent release. An application returning the expected result, which, however, formats incorrectly in a particular browser, is an example of a medium-priority defect.
#3. High Priority Defects
As the name suggests, high priority defects are those which have a high impact on the functioning of the software. In most cases, these defects need to be fixed immediately, as they can cause major disruptions in the normal workflow. High priority defects are usually classified as showstoppers, as they can prevent the user from proceeding further with the task at hand.
Some of the common examples of high priority defects include:
- Defects that cause the application to crash
- Defects that prevent the user from completing a task
- Defects that result in data loss or corruption
- Defects that expose sensitive information to unauthorized users
- Defects that allow unauthorized access to the system
- Defects that cause the loss of functionality
- Defects that result in incorrect results or inaccurate data
- Defects that cause performance issues, such as excessive memory usage or slow response times
#4. Urgent Defects
Urgent defects are those which needs to be fixed within 24 hours after being reported. Defects with a critical severity status fall in this category. However, low-severity defects may be classified as high-priority as well. For instance, a typo in a company’s name on an application’s home page doesn’t have technical impact on software, but has a major business impact, hence, is classified as urgent.
#1. Missing Defects
Missing defects arise due to the requirements that were not included in the product. They are also considered as discrepancies from the project specification and usually have a negative impact on user experience or Software quality.
#2. Wrong Defects
Wrong defects are those defects which satisfies the requirement but not in a proper way. It means that though the functionality is achieved as required but it is not up to the user’s expectations.
#3. Regression Defects
A regression defect occurs when a code change causes an unintended effect on an independent part of the software.
In the software industry, defects are an unavoidable reality. However, through careful analysis and understanding of their nature, severity and priority, defects can be managed to minimize their impact on the final product.
By asking the right questions and applying the correct techniques, testers can help ensure that defects are found and corrected as early in the development process as possible.