My first CCW pistol I just ran 2 boxes of FMJ through it without any feeding, ejection, or accuracy issues, ran a box of 20 of what my carry load was going to be. For me that seemed like enough "testing", accuracy was acceptable and no jamming or ejection issues with those loads. Took it home, cleaned the gun and mags, loaded the SD ammo in a mag, and put gun in the holster and considered it good to go. I did later on get practice drawing and firing, but did not do this prior to carrying.
I later switched to a more powerful caliber for my CCW, went through the same process. First 100 rounds were low powered factory ammo, ran 20 rounds of SD ammo through it and wan't impressed with accuracy of the SD ammo. Loaded up some hotter FMJ rounds and ordered up some different SD rounds to try out. Ran the hotter FMJ rounds without issue and found the SD load that had a nice balance of power and accuracy. Loaded up some more FMJ loads and some hot HP loads, and went out to the range with the holster and got practice drawing from the holster and shooting. That was something I didn't do with my first CCW pistol prior to carrying it. Once I was comfy with drawing and firing I cleaned the gun and mags, loaded the mag with SD ammo, put in the holster and considered it good to go.
Some things I guess I just take as a given for choosing a gun for CCW. One being comfort in the hand. If I pick up any gun at a shop and it doesn't feel good in the hand, I won't buy it. If it isn't comfy just holding it, its not going to get better when you are firing it. If I can't easily get parts, magazines, ammo, etc I will not buy it. I spent ALOT of time researching holsters and what features I liked and didn't like when I got my first CCW. When it came time for a new CCW pistol, since I loved the first holster it made choosing the new one pretty easy.