Different Types of Bugs That Arise During Software Testing

Bugs are bound to exist in a software. Whenever any new software is developed or an existing one is updated, various major and minor bugs tag along with it. These could be due to programming errors (errors made in either a program’s design or its source code), software complexity, etc. Testing engineers encounter these software bugs in their day-to-day QA operations, some of which appear more frequently than others. Today, we will be looking at the different types of bugs that arise during software testing.

Read: 6 Important Tips to Consider Before Outsourcing Testing

Types of Software Bugs

Before we walk you through the different types of software bugs, let’s first understand what a software bug is. In software testing, a bug can be anything that causes the software or the system to work incorrectly or behave in unintended ways. It can produce unexpected outcomes and may even lead to a system crash.

What are these bugs or errors that testers find during software testing? Let’s take a look.

1. Functional Errors

When the software isn’t in compliance with functional requirements and the functionality of the program isn’t operating correctly or the software isn’t behaving as intended, such errors are known as functional errors which are discovered through functional testing. The software seems to have caught a functionality error if something (that you expect it to perform) creates confusion and introduces complexity. Such software bugs can vary from unclickable buttons to the inability to use the primary features of the software.

2. Usability Defects

When a software application is found inconvenient to use or hampers user experience, it likely possesses usability defects. For example, if a user is finding it challenging to navigate around the website or app or it has a complicated registration process, it indicates poor usability. These types of software bugs are eliminated through usability testing.

3. Performance Issues

Performance issues are related to the software’s speed, responsiveness, stability, and resource consumption. An example of it can be a website or an application taking longer than expected to load. Such issues are highlighted during performance testing.

4. Communication Error

This type of error arises when there is a communication breakdown between software and the end-user, which creates troubles in the use of the software application. If the software comprises undocumented features, then communication error is bound to take place during its use. For seamless and effective communication between both parties, anything that the end-user needs to know in order to use the software should be clearly instructed to him on his/her screen.

5. Compatibility Issues

Compatibility issues arise when the software works excellently on one platform but fails to meet the same expectations on the other. In other words, software having compatibility issues doesn’t exhibit consistent performance across operating systems, hardware, browsers, and devices. To avoid software compatibility issues, test engineers must develop a solid architectural plan, prepare thorough release notes and perform customer outreach. This software bug type is eliminated through Compatability testing.

6. Syntax Error

The syntax error occurs due to an error in the program’s source code. If any aspect of the code does not comply with the syntax of the programming language, it will produce a syntax error. This is carried out during the syntax analysis phase.

These types of software bugs or errors are caused due to grammatical mistakes or missing operators. For example, a missing semicolon at the end of a code line or an additional bracket at the end of a function may result in a syntax error.

7. Calculation Error

This error or bug in software testing arises from calculation mistakes such as the incorrect implementation of the computational logic, coding errors, data type mismatch, mistakes in using the operators, functional issues, and lack of precision in the calculation.

In 1999, NASA lost its Mars climate orbiter due to a navigation error caused by a failure to translate English units to metrics, which caused the orbiter’s thrusters to work incorrectly and it crashed almost immediately when it arrived at Mars.

8. Logic Error

A logic error is a bug in the program’s source code that causes the software to behave unexpectedly or incorrectly. It’s a type of runtime error that may generate the wrong output or even lead to the program crash while running.

Note: Do not mistake this for a Syntax error. Logic errors are faults in the flow or logic of a program while syntax errors are errors in the syntax of a sequence of characters or tokens that are intended to be written in compile time. A program won’t compile until all syntax errors have been rectified. Unlike syntax errors, logic errors do not prevent a program from compiling.

Software Bugs/Defects Based on the Level of Severity

Bugs in software testing are generally classified into four parts based on their severity- Critical, Major, Minor, and Trivial. Let’s take a look at each of these.

1. Critical Defect

The defect usually blocks the entire system or software functionality, affecting critical data and functionality. It doesn’t have a workaround. Testing cannot proceed further without fixing this defect. Such defects include complete failure of the system, unsuccessful installation, or the application displaying a server error message after a signup attempt.

2. Major Defect

These defects do not crash the entire system but affect the key or major functionalities of an application. This causes the app to behave in a completely different way than what was stated in the requirements.

3. Minor Defect

As the term suggests, these defects affect the minor functionalities of a system and have an easy workaround. In other words, they do not have much impact on the system functionality or the workflow but can hamper the user experience. Broken links come under minor defects.

4. Trivial Defect

These types of bugs or defects have nothing to do with the system functionality and also don’t impact productivity or efficiency. They comprise defects that can cause a little bit of inconvenience to the user while they browse the application. For example- an inappropriate size or color of a button may put off the user.

Software Bugs Based on Priority

Software bugs or defects are categorized into four parts based on their priority- Urgent, High, Medium, and Low. Priority is often directly related to the level of severity, which means that a severe defect will be given the topmost priority.

1. Urgent

Defects having critical severity fall in this category and they need to be addressed as soon as possible, probably within a 24-hour period after being reported. It requires immediate attention as it severely affects the system and prevents the user from using it properly. The system won’t function until these defects are fixed.

2. High

High-priority defects are the defects that need to be resolved when some major features of the application are not functioning properly or in the way they are supposed to. These need to be fixed before the release is made.

3. Medium

This defect should be resolved during the course of software development. It can be fixed when you work towards creating a new version of the software.

4. Low

Low-priority defects are usually typing/spelling errors or cosmetic errors and can be looked into once all the above three issues are fixed.

Summing Up

By understanding the different types of software bugs, errors, or issues that you may come across during software testing, along with their level of severity and priority, you can fix those bugs at a better pace and improve the overall efficiency of your testing team.

There can be some cases where the priority is high and the severity is low or vice versa. For example, if there are some spelling errors in the logo of the company displayed to the users on the home page, this may not be a severe error since it is not affecting the system functionality but would be a high-priority issue from the brand’s perspective.

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