Software Developers as Testers – Myths and Reality

While there is no doubt about the role and the value of the dedicated software testers, there seem to be some myths about the ability of the software developers to perform testing and their value as software testers.

During the active development periods (before the completion of a phase or iteration) the developers have to code, participate in architecture and design discussions and there is no expectation to include them in the testing activities, although in reality they perform some testing by debugging their own code and writing and executing automated unit tests.

However, once the active development is finished there is usually a stabilization phase and the product has to be throughly tested and the defects have to be fixed.

During this phase there is little sense to have software developers waiting for the tester reports and doing nothing.

Unless there are dedicated software testing teams in the company, the testers in the project teams usually form 10 – 20% of the assigned resources. It may sound a lot, but in reality for a small team of 5 the mighty 20% means 1 tester and 4 developers. Is it a good idea to have one person doing the testing and four others waiting for some defects to be found so they can do some work?

Depending on the methodology and the QA process there might be a good reason for the developers to wait the whole reports before starting the fixing as it might be needed to prioritize the defects based on their severity and the available time.

In any case the goal is to utilize the available resources, so it might be a better idea to have the software developers doing testing instead of doing nothing. Is it really a good idea? Lets look at some of the myths.

Myth 1: Developers are bad testers as they are not willing to find defects.

Sounds logical as defects mean more work for the developers, reveal their mistakes etc., but in reality everybody with enough experience in our industry knows the defects are inevitable part of every product and would not take the defects found as a personal offence.

Some developers prefer to find their own errors before somebody else reports them, so they are very careful to find potential problems with their code.

In a successful team everybody is motivated to produce the best possible quality and take some pride for the results. If some of your developers do not care about the product they develop there is no need to give you an advice, you know what you should do with them.

Another motivation for the developers to find defects while testing is the understanding of the defects severity at the each phase of the product lifecycle. Defects found during the testing have much less severity than defects found after the product is implemented and could cause serious problems and financial loss. The developers are aware of this and have the motivation to prevent such defects with the final product as they may cost their job or seriously harm their reputation.

Myth 2: Developers cannot find all defects as they have built the functionality, know how it is supposed to be used and will test it the way they understood the requirements and the design documents.

While generally true, the reality is slightly different. It is a common sense to assign developers to test functionality build by other developers in the team, but even if this is not the case, many functional tests integrate several functions as part of a single scenario and the developers often see the functionality they have implemented from a new perspective and often try different usage scenarios.

Due to the functionality integration it is also very common the same function to be executed and tested directly or indirectly as part of several scenarios performed by different testers (developers).

It is important to understand that the developers are supposed to perform as testers mainly in the stabilization phases. During the development phases the dedicated testers are responsible (on a daily basis) to check any completed functionality for discrepancies with the requirements and the expectations.

As the testers prepare testing scenarios and the testing performed during the stabilization phase is mainly based on these scenarios (with little or almost no exploratory testing), the developers practically perform as dedicated testers as they usually simply follow predefined scenarios of test steps and use predefined test data.

Myth 3: It is impossible to motivate developers to perform testing tasks.

Most of the developers hate (explicit) testing – they find it boring, low profile, not creative etc., but there is something we should not forget – software developer, designer, tester – all these are roles, but behind the roles there are humans and depending on their personality they might be willing to help each other.

Usually the first time the developers are asked to help with the testing they are rarely positive, but once they are involved and go several times through this process they start understanding the testers work and appreciate their effort. We are all different, but the majority of the people would prefer to help each other, so the four developers in our example might be willing to help the single tester in their team during the important stabilization phase.

We should not forget the motivation caused by the potentially negative consequences by defects not found by the team and revealed in the product usage. It questionable whether this is a good motivation or not, but it always works as most of the people care about their own reputation and do not want to be guilty for some serious problems.


Are the myths busted?

Yes and no. Or in other words – depends. It depends on the personality of the developers, on their willingness to build a great product and the management ability to motivate them.

Should we have only developers in a team and no dedicated software testers – definitely NO. The developers could help a lot with the testing, but this remains a help, it is not their primary duty and there should be testers to perform exploratory testing, prepare and execute test scenarios and perform quality control on a daily basis.

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