I know CCP has said they're working on building a test range. With the importance of testing fits, I think it would be great if we could get an unpolished version sooner > later. Here's what would be one way to quickly implement the mode. Use one of the existing maps and spawn in static npc players and vehicles with progressively better stats the closer you get to the other side. You can call up a test skills window, and a test fits window and select your skills (The color of the skill window would be red or something just to be clear that this is only for testing) with infinite SP available and also select your weapon/fit that all cost 0 ISK.

You can approach any enemy NPC or vehicle and push "O" and you'll be able to select any skills/fits for them as well. You will also be able to "wake them up" either aggressively or defensively. An NPC on defense will sprint/dodge/juke/weave/bunny-hop around and hide behind cover in a 10m radius or so. An NPC vehicle will drive/fly along a pre-defined path. The AI can be very simple and not clever (e.g. if the NPC guy/vehicle gets hung up on the geometry, it's no-big-deal). On agressive, The NPC will try to kill you as best it can until it's destroyed, and if it's a vehicle it will use it's weapons to shoot you after a delay of x seconds. This allows you to see how well your tank can withstand incoming fire for example. Again, the AI can be very generic/basic and buggy. This is only for testing. Once killed the NPC will respawn after a brief delay and return to its original static state.

This mode could be created with minimal effort reusing 100% existing assets. The only major coding effort required would be for the AI components, but these can be very simple and buggy. The hard part about AI programming and the thing that takes the most time/effort is debugging the edge-cases. Here a quick/dirty AI that a CS college intern could whip-up for an assignment would probably be sufficient. Perhaps, they could reuse an existing AI engine. The main point is that minimal resources/effort could be expended on the project, and the benefits would be tremendous. At some point they're going to have to create an AI anyways in order to implement the PvE modes they're working on. Who knows, maybe they've already coded something they can use. It would also be a nice way for CCP to play test their AI.

I'd love to see a custom-designed, highly polished test map/facility one day. I'd much rather see something crude and useable get released quickly in the meantime. I suspect this might also help with player retention, by giving people more things to do, and allowing new players to practice and get a feel for the weapons outside of being massacred in pub matches. It also allows people the option to try before they buy regarding skill point investments. And it gives the players something to look forward to working towards if they put in the time and effort.