Disclaimer: Everything is at your own risk.

I would first check softness with thumb, compared to surroundings. Soft? Fail. Still feels rigid? Proceed to next test.

Tap test like others have said. Sound OK?

Borescope would be good, to see if cracks extend to inside the tube.

Then I would carefully chip off paint, examine, then touch up the paint. But perhaps not if it passes all above tests.

Part of the reason I am saying the above is that the top tube is not the highest stressed part of the frame, and that's a pretty fat tube. That kind of damage on skinny chainstay or seatsay, would be more critical. Not saying the above is "fine", but you have a bit more margin.

What style of bike is it? Road? Mountain? Downhill?