Comment: I am a software tester. (Score 4, Informative) 219
I'm a software tester for data moving products.
While a lot of testing is repetitive, the repetitive stuff can often be automated. For example, there's functionality that exists in every release
For new features, what typically happens in my group is that the developers will explain how they implemented a given feature and how it should work. We are responsible for testing this feature - with any tips that dev gives us - as well as trying to put it through various scenarios that cause it to break.
In my product's line, for example, we do clean reboot and power cycle/crash testing. What happens to our product when the power goes out? What happens to the data that was being moved? Does it recover? That sort of thing. This requires thought - and, contrary to some comments here, since we all want our business to SUCCEED and make money, which means customers need to be happy with the product, development is happy when we find errors or scenarios that they did not plan for in their coding. The earlier we find them, the better.
Day to day activities? Well, I'd break it into two major sections.
Planning
The test group, in my case, is responsible for reading through the planned product's features and changes and coming up with a test plan accordingly. This is then reviewed by developers, the test group, etc. Usually, during this time period is when a lot of work on automating previously-manual testcases can be done, in preparation for the next release. Also, planning for what testing environments will need to be setup and starting to set them up... it depends how big your group is I guess. Since mine is relatively small, all the testers help out with setting up various machines for testing, too.
Testing
During testing, the test plan is executed. Day to day activities include test environment setup, manual testing, automated testing, discussing potential issues with developers and opening work requests (WRs) if it's decided that it is really an issue and not a weird environmental problem etc.