Software Testing - mindset

I've been working as a test engineers for a few years. And if someone ask me "what is the most important thing for test engineers have to have?", I would say it is the mindset. What differentiates test engineers from development engineers? What are the things we(test engineers) are specialized in?

If you cannot answer those questions, you need to read the rest.

To answer those questions, I need to talk about bugs. What is a bug? Who writes a bug? We all know that there is no bug free software. Yes, we are humans and we make mistakes. Developers cannot write bug free code.

From my experience, there are two kinds of bugs. The first one is the mistake developers make while they are writing codes. He/she coded incorrectly and the code does not work the way it should. The other one comes when they miss some possible situations. He/she did not handle null case or did not handle really big input or did not handle negative value and so on.

The first is normally straight forward. We can easily get all the possible permutations or possible expectations from the spec or the context. I think the latter is the part we(test engineers) are specialized in. Possible situation is not about inputs for some functions. It's about considering all the possibilities that will affect the application. We are so good at figuring out what those pieces of code or thousands lines of code will face. We are also good at prioritizing the situation in terms of business perspective and software development perspective.

A good developer is capable of writing good code in any kind of application, environment or language.

A good test engineer is capable of coming up with good possible situations whether it is one method, components, client applications, web applications or enterprise applications.

Going back to mindset.
Test engineer's job is not making sure the application works as spec states. It's about understanding the aspects of the development process and figuring out important situations that the application will come across.