Smoke alarm (optical) from #AliExpress failed the smoke test. It feeps loudly when pushing the test button, but when held into some nice fire smoke, it does exactly nothing, despite patience.
So always test with a real life scenario. The test button only checks the batteries and the beeper are working, not the actual sensor.
I sent them a nice video and expect a refund. This isn't because it's from China, the same can happen with any.