The way I tested my Gore Jacket involved having a clipped-in moment and rolling sideways down off the trail several feet into the river below.
All of me was soaked except my arms and torso. I was impressed.
On a similar note, my first ride with my new Specialized Submerge gloves involved me crashing and ripping the glove just above one of the knuckles. When it rains, that knuckle gets wet, the other hand doesn't. So they work too.