[Test] Heterogeneous env

[matteobettini]

@vmoens @hyerra

This improves the test in #1204

Look at the spec of this env.

In my opinion it should cover all heterogenous use cases apart from composite actions, can you think of something I missed?

[hyerra]

Thanks, this looks really good for the heterogeneous part! One suggestion though, is it possible to have a test for where agents have a different number of observations? This is possible in Unity, for instance. For example, maybe agent 1 has both lidar and camera, but agent 2 only has lidar.

[matteobettini]

Thanks, this looks really good for the heterogeneous part! One suggestion though, is it possible to have a test for where agents have a different number of observations? This is possible in Unity, for instance. For example, maybe agent 1 has both lidar and camera, but agent 2 only has lidar.

are you referring to the fact that the obs tensordicts have the same number of keys? would it cover your case if I remove the sonar from agent 2?

[hyerra]

Yep, exactly, that case should cover it! I'm not sure if this case was what caused the bug in the StrikersVsGoalie game to fail. I didn't fully debug it just yet, but that was my initial guess.

Edit: Oh wait, actually on second thought, I think I understand now why the StrikersVsGoalie game failed. It wasn't because of the number of keys. I'll update the Unity PR to discuss this more there.