feat: Enable stashing of expected messages

There are cases where we need to access the message that was
just decoded within the `ExpectMsg` event.

This commit adds a generic method to the stash module,
allowing retrieval of information from the message.

Furthermore, starting from this point, lnprototest will stash
all messages that are decoded using `ExpectMsg`. This enhancement
simplifies cross-compatibility efforts with other implementations.

Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>

lnprototest/dummyrunner.py

@@ -49,7 +49,7 @@ def has_option(self, optname: str) -> Optional[str]:
     def start(self) -> None:
         self.blockheight = 102
 
-    def stop(self) -> None:
+    def stop(self, print_logs: bool = False) -> None:
         pass
 
     def restart(self) -> None:

lnprototest/event.py

@@ -346,6 +346,7 @@ def action(self, runner: "Runner") -> bool:
             # Might be completely unknown to namespace.
             try:
                 msg = Message.read(namespace(), io.BytesIO(binmsg))
+                runner.add_stash(msg.messagetype.name, msg)
             except ValueError as ve:
                 raise EventError(
                     self, "Runner gave bad msg {}: {}".format(binmsg.hex(), ve)

lnprototest/stash/__init__.py

@@ -28,26 +28,5 @@
     htlc_sigs_to_recv,
     locking_script,
     witnesses,
+    stash_field_from_event,
 )
-
-
-__all__ = [
-    "commitsig_to_send",
-    "commitsig_to_recv",
-    "htlc_sigs_to_send",
-    "htlc_sigs_to_recv",
-    "channel_id",
-    "channel_announcement",
-    "channel_update",
-    "get_member",
-    "rcvd",
-    "sent",
-    "funding_amount",
-    "funding_pubkey",
-    "funding_tx",
-    "funding_txid",
-    "funding",
-    "funding_close_tx",
-    "locking_script",
-    "witnesses",
-]

lnprototest/stash/stash.py

@@ -273,3 +273,14 @@ def _funding_close_tx(runner: Runner, event: Event, field: str) -> str:
         return runner.get_stash(event, "Funding").close_tx()
 
     return _funding_close_tx
+
+
+def stash_field_from_event(stash_key: str) -> Callable[[Runner, Event, str], str]:
+    """Generic stash function to get the information back from a previous event"""
+
+    def _stash_field_from_event(runner: Runner, event: Event, field: str) -> str:
+        if runner._is_dummy():
+            return "0"
+        return runner.get_stash(event, stash_key).fields[field]
+
+    return _stash_field_from_event

tests/test_bolt2-01-open_channel.py

@@ -33,6 +33,7 @@
     funding_txid,
     funding_tx,
     funding,
+    stash_field_from_event,
 )
 from helpers import (
     utxo,
@@ -110,7 +111,7 @@ def test_open_channel_from_accepter_side(runner: Runner) -> None:
             delayed_payment_basepoint=remote_delayed_payment_basepoint(),
             htlc_basepoint=remote_htlc_basepoint(),
             first_per_commitment_point=remote_per_commitment_point(0),
-            minimum_depth=3,
+            minimum_depth=stash_field_from_event("accept_channel"),
             channel_reserve_satoshis=9998,
         ),
         # Ignore unknown odd messages
@@ -203,7 +204,7 @@ def test_open_channel_opener_side(runner: Runner) -> None:
             max_htlc_value_in_flight_msat=4294967295,
             channel_reserve_satoshis=9998,
             htlc_minimum_msat=0,
-            minimum_depth=3,
+            minimum_depth=stash_field_from_event("accept_channel"),
             max_accepted_htlcs=483,
             # We use 5, because c-lightning runner uses 6, so this is different.
             to_self_delay=5,