How could we observe a wormhole? A wormhole is a sort of tunnel that could connect two points in spacetime. These are theoretical objects that have not been observed. What observational evidence could we look for to confirm (or disprove) their existence? If they do exist, what should we be looking for to find one?

This answers how wormholes could be created. This is not what I'm asking about. I want to know what observations could be done (potentially with telescopes we don't have yet) to confirm the existence of wormholes.
One plausible way of detecting wormholes (paper) is gravitational microlensing. Light paths are bent by the curved spacetime around the wormhole, similar to what happens near black holes. As a wormhole moves in front of background stars it can cause the brightness to vary in a characteristic way, making it possible to distinguish it from a black hole. 

One of the problems is that there are many possible wormhole models, so the light curves can look different. Some can also produce multiple Einstein rings, others none. However, this may in theory be good news for learning what model is right if one sees a really weird light curve. In practice, given noise and lack of observations, multiple explanations will likely be possible for a long time if one sees just one example.