[Portal 2] HOWTO: Test Co-Op maps alone
This is a guide on how you can test co-op maps alone. This also works for any existing coop maps. It does not require you to do anything special with the map file itself. Thanks to the early posters in this thread and various people on the Source forums for the information, I just assembled it all in one place.
The following gets you started:
ss_map mapname: Load mapname in splitscreen mode.
ss_splitmode 0: Side-by-side split
ss_splitmode 1: Top-and-bottom split
If you run dual monitors and want to split to each monitor, follow the guide here: http://forums.steampowered.com/forums/s ... ?t=1857198
Controlling the second player:
There are a number of ways you can do this:
1. Use in_forceuser
This lets you "take over" the second player. It is flagged as a cheat, however, so cheats need to be enabled.
sv_cheats 1: Turn on cheats
in_forceuser 1: Control second player
in_forceuser 0: Control first player
I suggest a keybind for this:
BindToggle "z" in_forceuser
Swaps you between first and second player.
2. Use a controller
This is actually more complicated than it sounds, unless you have two controllers. There doesn't seem to be a way in Steam to bind actions on the first controller to actions for the second player.
More information for this can be found here: http://forums.steampowered.com/forums/s ... ?t=1847904
3. Use change_portalgun_linkage
This lets you create multiple sets of portals as one player, so isn't truly playing two players.
It's not yet tested to see if portals that are in the set you aren't currently linked to survive going through a fizzler.
I recommend the first option -- it's the easiest to set up, and doesn't require you to jump back and forth between mouse+keyboard and controller.
Of course, if you really are testing with two people, the second option is probably your best bet.
Try remove the mp_ tag on the mapname maybe? 
Since that prolly wont do shit, try decompiling the map, i noticed most maps have these dedicated boxes with entitys for mp, im sure you could fiddle with those. to achieve support for both sp and mp (and i guess you will need them for proper functioning coop anyway)
What you could do is use visgroups to change what entities the map is compiled with. Mark the info_player_start as part of a custom visgroup called "1 player" or something and the coop starts as part of "2 players". Then you can select which one to use before you compile. This will also allow you to test puzzles as a single person that wouldn't be possible otherwise e.g., have cleansers and walls that are only part of the "2 players" group so that they won't hinder you when testing by yourself. I use this feature all the time if I need multiple versions of a map.
Portal 1: Portal Pro, Resurrection, Dyad, Rexaura
Portal 2: [Coop] Electrophobia, [PTI] EotM Collection, [SP] Aperture Halloween
You can try running a map in splitscreen mode. If you have a gamepad you can than test with both players.... one by one 
it is possible. the map "coop_spawn" has a compilable version of a minimalistic coop-spawn that is palyable in singleplayer.
Thanks for the replies. Based on them and some other information I've gathered, I'm going to edit a HOWTO into the opening post shortly.
Great! I didn't know you can switch players. With that you can fully test a map without any problems (gamepad can cause some issues and i'ts not that easy to set up). Of course for fast paced maps and the ones where both players have to do something at the same time this won't work... I suggest cloning yourself 
Thanks for the info
So is the first post now a complete how-to on how to solo-test a coop map?
Please do not Private Message me for assistance. Post a thread if you have questions or concerns.
If you need to contact the staff privately, contact the Global Moderators via Discord.
Yup.
Cool. Sticky'd. You should probably post this on the VDC too.
Please do not Private Message me for assistance. Post a thread if you have questions or concerns.
If you need to contact the staff privately, contact the Global Moderators via Discord.