You should not attempt to test a condom yourself. (See other post.)
The “test” is circumstantial:
All condoms1 are tested at the manufacturer’s, individually, before packaging. This is certified on the packaging and guaranteed for a certain time, provided correct storage conditions etc. are maintained. Your assessment of the usability/safety of the condoms hinges on whether that state is maintained between the product leaving the factory and you using it. In short, start with the assumption that the condom is safe, discard any where there’s any doubt that they are no longer, for whatever reason.
- If you can be reasonably sure that these conditions (e.g. temperature range) were maintained, the condoms should be fully functional until you intend to use them, at least until the given date on the packaging.
- Any sign of tampering (even inadvertently) means that the product is to be considered “not safe” (which doesn’t necessarily translate to defective), so don’t buy the ones where the box is damaged. And don’t use those where the individual packaging isn’t like a slightly inflated cushion or deflates when pressed.
- Follow the instructions for use, that includes opening the packaging carefully and keeping all sharp and pointy things away. So no dramatic “ripping the pack open with your teeth”, sorry.
So the responsible answer to the question for a lifehack must be: Don’t attempt to hack it, follow the instructions.
1 assuming the genuine medicinal protective item, not novelty items that are “toys” and were never intended as true form of protection