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3 reasons why most good developers make poor testers

Posted by Dan Berry on Tuesday 21 November 2017

As your user demands escalate, it’s increasingly difficult to create robust applications that work across multiple devices, platforms, languages and use cases, especially under the ever-demanding timescales.

As such, your web testing processes may get pushed to the sidelines as you rush to push your latest release. You may decide to rely more on your developers to quickly test your latest update or new service to save some time.

This is a massive mistake.

Your developers should never be relied on to test your code. It isn’t the best use of their skills and they may fail to recognise bugs in the same way as a professional tester would.

pexels-photo-392018.jpegThe end result? Your users are given a bug-filled website or app and your conversion rates plummet. Using your developers to test your code may seem like a quick win on the surface - but it’s one of the biggest web testing blunders you could make.

Why? Because your developers are not cut out to test their own code. Here’s why: 

1. Most developers do not have a test mindset

Testers and developers have completely different skill sets and mindsets. When faced with a user story, a developer will pull together their knowledge and experience to create patterns and find the more effective way to achieve the story’s requirements. Most often, a developer does not focus on the user, but finding a solution to a problem.

A tester takes the opposite route. They look at a user story and try to find problems with the developer’s solution. They do this by taking the user’s perspective and try to break any patterns the coder has integrated in their work.

Testers will also have more experience with common issues and application pitfalls. They know what to look for and will automatically use this knowledge when they start testing.

This can be quite a painful process for the developer. For example, a developer may spend days carefully coding a beautiful landing page, only for a tester to find it does not work on certain mobile devices.

For a tester to come along and, effectively, break your work as a developer, can be disheartening - but you can’t afford for your developers to get sentimental about a chunk of code. Thorough testing is an absolute necessity to produce the best website or app for your users.

2. Developers are used to writing code

It’s an obvious statement, but your best developers are used to writing code and following the procedures and pathways that have always worked to produce the best syntax.

Developers focus on producing a website that works effectively and efficiently. It can be difficult to retrain your developers’ brains to work in the opposite way and find things that are wrong and do not work.

As a result, your developers have a different focus when they test their code. They may only test things at the forefront of their mind. For example, if a responsive design was struggling on a certain device during development, they may focus on that device and fail to test on other devices.

Or, if they have been asked to add one new feature, they may fail to look for and identify knock-on defects elsewhere in the code.

However, a tester will test an entire application with one goal in mind: to make sure it fails.

3. Differences in attention to detail

A developer testing their own code is a dangerous thing. If you’ve been working on a solution for days or weeks, it’s easy to become complacent. So, your developers may struggle to find defects in a piece of software they have been working on continuously for weeks.

What’s more, they may not want to find bugs because, quite frankly, they want to move on and work on something else.

Developers are also unlikely to have the attention to detail to carry out robust web testing. We typically find that testers find 10 bugs for every bug a developer identifies.

This is especially true when it comes to visuals. A tester will view your website or app from the user perspective and identify issues that a developer may not even consider. For example, what happens if a user presses two keys at once or clicks the “back” button while a page is loading?

The longer a developer spends looking at the code, the less likely they are to spot even the most obvious of issues.

In conclusion, good developers are often poor testers and poor testing means more critical bugs make it to your customers. If you want to review your approach to web testing, click here to read our web testing checklist.

Web Testing