You could test with air, depending upon the material used. You can't test plastic with air but you could with copper. You'd have to isolate your new piping and get an air compressor. Pump it up to 50lbs minimum for 30 min. Some people pump it up to 100lbs just to be sure but unless you're a pro I wouldn't recommend it. Some fittings that were never soldered or glued could hold a test for some time and never blow. I would just turn the water on and have someone stand at the main shutoff and another stand by with a bucket and some towels. Remeber you can't test plastic pipe (cpvc, pex) with air so if you used those materials you're gonna have to do a standard water test.