The fable of “Boiled Frogs” says that if you drop a frog into a pan of boiling water, it will jump out immediately, but if you put the frog in a pan of cold water, and slowly increase the temperature, it will stay there until it is cooked.
I haven’t tried this personally, but I see the analogy often in software testing. Many of the pragmatic programming tips apply equally well to testing and development, and this is no exception, but I think it’s worth calling out as a testing tip because I see it so often in testing. I’ve seen numerous cases where a tester was so focused on completing the testing of their component, that they didn't notice that the integration criteria had begun to fail; that performance numbers were unacceptable; or that the user requirements were not being met.
It’s extremely important to take a step back from time to time, look at the big picture, and take note of what is changing. As a tester, you are responsible for verifying functionality and finding defects, but you are also responsible for being the eyes of the customer. Customers don't buy your product to use one feature, they buy your software so they can use the entire product. Keep an eye on change, and make sure that any gradual change you see is improving the quality of what you are testing.
Now tasting: 1999 Trinchero Chicken Ranch Cab Sauv.