Add tests for item possession in goal criteria

[kostmo]

Towards #858

[kostmo]

This does not succeed even after grab-bing the tree.

[byorgey]

I've been poking at this a bit. Curiously, I've found that it does work correctly if the test is wrapped in a try block, like this:

      as base {
        try {
          itemCount <- count "tree";
          return $ itemCount > 0
        } { return false };
      };

In theory this should not make a difference.

[byorgey]

The runtime code for has and count is almost identical. The one big difference between them which seems like it might be relevant is that has does not require any capabilities to use, whereas count requires a counter. But in theory the condition checking robot should be able to use count whether base has a counter or not (and indeed, if I add a counter installed on base it does not change anything).

[xsebek]

Hmm, maybe base can not count or something?

[byorgey]

I really want to figure out what exceptions are being thrown but I'm not sure how to export that information. @xsebek, any ideas?

[xsebek]

@byorgey I just checked by printing exceptions from the hypothetical check and there are none.

I just added this:

sendIO $ putStr "ERROR: "
sendIO $ print m

here:

swarm/src/Swarm/Game/Step.hs

Lines 137 to 146 in e73a284

	-- Log exceptions in the message queue so we can check for them in tests
	Left exn -> do
	em <- use entityMap
	time <- use ticks
	let h = hypotheticalRobot (Out VUnit emptyStore []) 0
	hid = view robotID h
	hn = view robotName h
	farAway = V2 maxBound maxBound
	let m = LogEntry time ErrorTrace hn hid farAway $ formatExn em exn
	emitMessage m

Weirdly this is also a transformation that fixes the condition:

t <- time;
if (t < 0) {return true} {
    as base {
        itemCount <- count "tree";
        return $ itemCount > 0;
    };
}

[xsebek]

Looking at debug logs (see the debug branch), the count is correct: