Soldered joints usually don't break (unless you are talking about the wire just after the joint).
If you are soldering two wires together, the strands should be twisted together first. After soldering the solder surface should be smooth and relatively shiny. It should "wet" the wire strands. This is most easily seen if you clean the solder joint with alcohol before inspecting.
While a DVM will certainly show a very very bad solder joint I doubt it will find a marginal one.
If you are soldering to a lug or some such the same applies except the wire cannot be twisted but should be looped or in a "J" configuration and squeezed on the lug before soldering.
Adafruit as a article on soldering that might help Soldering