Big developers will often have a testing or QA department but the jobs will tend to be short term. When they have a big title coming up for release they’ll hire in a team of testers to cover it for a few months. If they have enough titles on the go they may have permanent testing staff. Working at a developer it is highly likely you will be testing the same game for several months. Even if it is your favourite title believe me you will come to hate it after so many hours and all you’ll be able to see are the flaws. Many developers now outsource the testing or rely on publishers to cover it.
Publishers also employ testing teams, increasingly located in Eastern Europe or India. The good thing is game development is a 24 hour business and so it is common to have test teams in various places around the world working in shifts. Working as a game tester for a publisher will allow you a bit more variety as they will likely have a number of titles and you will work on them short term. The upside is the variety, the downside is the fact you can’t go next door and talk to the dev team about a bug because they are probably miles away.
You could work for an outsource company that specializes in testing. You’ll perform the same function as an internal test team but remotely. Some assignments may be short term others may last months, it just depends what the developer needs.
The most attractive testing jobs of all are for the big console manufacturers. They test all of the titles that come out on their consoles and this means lots of variety. You’ll get sneak peeks at the latest titles but it is unlikely you’ll have to play any of them for too long and they’ll be in a near finished state.
Developers and publishers regularly advertise testing roles. They will typically take on extra people when they have a specific big title nearing release and so while you may start off on a temporary contract, if you do well you’ll be able to secure more work. To improve your chances of getting an interview in the first place take part in Beta tests online. You can also try to identify bugs in existing games and think about how you would highlight them and recreate them. There are a number of websites online which claim they will get you testing work for a fee - never use them! They are a complete scam. You should never have to pay in order to secure a job.
The game tester job is an entry level role and so sometimes you can secure one without any previous experience. Some people see testing as a gateway role which can lead onto other things and while this can be the case, you may find some companies who don’t recruit from their test department for other roles so don’t assume it will happen. If you intend to do this it is best not to tell the test manager at your interview because they are generally looking for committed staff, not people who view the job as a stepping stone.