Where do software bugs come from?

Łukasz Kołpak
09 June 2020
4 min read

Software bugs (or defects) are pretty much as old as the software itself. With modern software getting more and more complex, the projects are not only richer in features, but also more prone to bugs. But why does software have bugs? Where do they come from? And finally, how to prevent software bugs in your project development?

What is a software bug?

A software bug is simply an issue that causes the program not to show the desired behavior. Usually, bugs lead to the program crashing or producing an unexpected result. While the majority are quite trivial, like spelling mistakes. Some software bugs can have serious consequences and cost people's lives.

Now, let's be honest: there are no bugless applications, only apps for which the bugs haven't been found yet. Fortunately, with time and resources, there are appropriate ways to find and eradicate them. Let's go through some of the most frequent software bug causes and the ways to mitigate them.

What are the types of software bugs?

Software bugs caused by human errors

Unsurprisingly enough, the most frequent cause of software bugs is, of course, human errors. Typos, improperly written functions, logical errors, you name it. There is no way to avoid these entirely: we are humans and not machines. A bad day, a broken coffee machine (or both) can lead to potential issues. However, there are ways to counteract them other than by supplying a new coffee machine quickly (a happy dev team always generates fewer bugs, that's a fact). 

As for catching these issues, there are several ways to defect mitigation. First of all, having a dedicated QA in your team improves the rate of finding these issues massively. It is kind of a no-brainer that a Quality Assurance Engineer is the best person to do so, as, well, it's his primary goal. Another layer of protection against bugs is code review: having another developer peer-review one's code is a blessing. It ensures that the code is not inherently faulted in a way that non-developers often cannot see.

Software bugs caused by regression

The second cause of faults in the software is regression. Regression is adding bugs in an already developed feature by introducing another feature. It's caused mostly by the fact that seemingly separate features share some common code. Changing it may unexpectedly cause degradation in other areas of the application. 

The most common way of counteracting it is through regression testing that checks if any part of the app suffered some degradation of quality. The most reliable way to do so is to introduce end-to-end automation. In simple terms, there's less room for errors if we check if the added features actually work. Of course, developing and maintaining tests takes time, but it's an effort that pays off.

Software bugs caused by faulty logic

The logic of the application influences the number of bugs. In the app's lifecycle, there's a time when the QA wants to "do that A thing while also doing the B thing." Well, this often results in a significant bug. Or, a feature may look good on paper. After implementing it, there are a lot of cases that were not thought through properly, causing a need for a major rework of said feature. Such issues may be costly to fix, especially during the late stages of project development. 

So, how does one tackle this issue? The best solution is to involve the QA at the earliest stage possible so that the problem can be spotted at the beginning when the cost of fixing this mistake is the lowest. As soon as there are any requirements for the application, the QA can start doing what he does best: finding issues. It's the best example of why hiring a QA can lower the cost of the project.

Software bugs caused by compatibility issues

For a change, here's a bug that cannot be accounted for as a POBCAK type of error. It's quite simple: all devices and browsers have slight differences in terms of how they handle applications and websites, therefore creating issues. There's no way to avoid these issues, unfortunately. But do you absolutely need that IE11 support for your website? Or Android 4.2 for your mobile app... :) 

We're happy to advise the best set of browsers/devices based on your needs. Speaking of it, the best practice is to define the scope of those at the beginning of the project. This way, the product is tested on the agreed scope throughout its lifecycle. That way, the defects related to compatibility are not left as a surprise for the end of the development.

Lost in translation

Given the complexity of many projects, the development teams often consist of many people working together to deliver the working product. However, this creates an opportunity for more bugs to appear due to things being lost in translation. Just as in the telephone game, the information transferred from one person to the next may change its meaning or be lost altogether, causing a change in the requirements, which equals a bug. 

An (im)perfect example of such a situation is the design of the application. If it leaves quite a room for interpretation, it can be challenging to convey certain features on a still picture. In this scenario, even an experienced developer can misinterpret something. And hey, presto, that's a bug. 

While finding the bug relies on the Quality Assurance Specialist, a Project or Product Manager has a far more critical role in this scenario. It's this person who is responsible for making sure that correct information is passed to all concerned parties, and that the gathered knowledge is valid.

Coming to terms with software bugs

Defects in the software are unavoidable. Just as in our lives, not everything can be done correctly on the first try. Mistakes happen, no matter what. However, by knowing why software bugs occur, we can take the appropriate actions to mitigate the risks involved in the product development process. Being a software house, we have built procedures designed for delivering the best possible quality.

Having the right people at the right time combined with solid know-how is the key to successful delivery, and ultimately, a happy end-user. Would you like to know more about how we work and what we do? Get in touch at hello@start-up.house

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