I noticed my shower was leaking when I saw water on the lower wall in my living room. To try and find the problem I didn't use the shower for 3 months to let it hopefully dry out.
I then did the following to attempt to find the problem.
To test the drain I ran water down it from an outside source for 10 minutes, no leaks. To test the pan I plugged the drain and filled (outside source) the bottom of the shower as high as I could, about 5 inches, without it spilling out and left it for 20 minutes and still no leak. To test the incoming water pipes I ran a hose from the showerhead pipe to my backyard and ran the hot and the cold water for 10 minutes each, individually, and at different volume, still no leaks. I am stumped. Thanks