Question: My probation period is ending soon, and my boss asked if I want to continue with the technology I was using, or to change to other one.

I have to announce my decision on the last day of the probation period. Changing doesn't make a lot of sense, which makes me wonder if I choose wrong, will that be my last day.

So my question is is it common and widely accepted to test person's worth and motivation by setting this kind of tests?

(This is not a company-specific question, but more like "do these kinds of habits and company cultures exist?").

Answer: 
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> This is not a company-specific question, but more like "do this kind of habits and company cultures exist"
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Clearly such things do exist or you wouldn't be asking the question but in my 30+ years in the workplace, I've never heard of it. It's an interesting question to be sure.

I can understand why you would be suspicious of it as a trap, especially if you have to "announce" a decision rather than a preference.

Were it me, I'd answer honestly. It may well be a trap but there's not a lot you can do about it. Answer with your honest choice but follow it up by saying, "but I understand that the needs of the company obviously are important and so I'm willing and happy to go where needed."

Make it clear that you're a team player and you'll go where they need you to go if you're willing to do so. 

Something else you might consider is the place of the "other one" in the company. Your boss could be offering you an opportunity that you might otherwise have. For instance, if you're working on a technology that is still well-used but the company has plans for something different, that might be something to consider. For instance, if you're an Microsoft person but the company will be transitioning to LAMP, they could both have a strong need for the future, but the longevity of the other could be greater.

Also, perhaps your boss is testing you in a way you hadn't considered, giving you the opportunity to ask "where am I most needed?" or maybe even a simple, "what do you think?" to show that you value (or at least consider) his opinion. I could definitely see a question like that being used to see how focused you are on company needs versus personal desires.
It's very unlikely that this is a trap. However you can use this opportunity to your benefit.

The important thing is not to just pick a technology because you like it, or because it's new. **Talk to your boss and ask what changing technology will mean**.

* Ask what projects you will be working on with both technologies;
* Likewise ask who you will be working with, and who your boss will be in both cases
* Ask which one the company sees as growing, and which might be key to the company
* Assuming you get on averagely well with your boss, ask him which he would recommend