If you don't have any fancy equipment, you could sort of test them as follows:
- Connect them to a power supply through a series resistor (like 1k ohm or a bit lower), set the power supply to max rated voltage (25V);
- This will charge them and eventually get ~25V across them. Leave them like this for a week or so;
- Come back and check for any bulging or leak;
- Disconnect the power supply, connect the capacitor to an oscilloscope's probe, connect a resistor across the cap to discharge it (ideally through a switch), then put your scope to single shot and close the switch. Now observe the discharge curve, and calculate from it the approximate capacitance. Compare that to the nominal capacitance.
This won't tell you if they'll be fine after 10 years of operation, but should give you an idea of how usable they are.
And if you don't have patience for that, you can always use them as firecrackers as I suggested. It's more fun than you may think (if you're into firecrackers and things exploding in general.)