test: fix assert_debug_log call-site bugs, add type checks

Two recently added tests (PR bitcoin#28625 / commit 2e31250
and PR bitcoin#28634 / commit 3bb51c2)
introduced a bug by wrongly using the `assert_debug_log` helper.
Instead of passing the expected debug string in a list as expected, it
was passed as bare string, which is then interpretered as a list of
characters, very likely leading the debug log assertion pass even if the
intended message is not appearing.

In order to avoid bugs like this in the future, enforce that the
`{un}expected_msgs` parameters are lists.

Author: theStack

test/functional/feature_assumeutxo.py

@@ -82,7 +82,7 @@ def test_invalid_snapshot_scenarios(self, valid_snapshot_path):
             f.write(bytes.fromhex(bad_snapshot_block_hash)[::-1] + valid_snapshot_contents[32:])
 
         expected_log = f"assumeutxo height in snapshot metadata not recognized ({bad_snapshot_height}) - refusing to load snapshot"
-        with self.nodes[1].assert_debug_log(expected_log):
+        with self.nodes[1].assert_debug_log([expected_log]):
             assert_raises_rpc_error(-32603, "Unable to load UTXO snapshot", self.nodes[1].loadtxoutset, bad_snapshot_path)
 
     def run_test(self):

test/functional/p2p_segwit.py

@@ -706,14 +706,14 @@ def test_p2sh_witness(self):
         # segwit activation.  Note that older bitcoind's that are not
         # segwit-aware would also reject this for failing CLEANSTACK.
         with self.nodes[0].assert_debug_log(
-                expected_msgs=(spend_tx.hash, 'was not accepted: mandatory-script-verify-flag-failed (Witness program was passed an empty witness)')):
+                expected_msgs=[spend_tx.hash, 'was not accepted: mandatory-script-verify-flag-failed (Witness program was passed an empty witness)']):
             test_transaction_acceptance(self.nodes[0], self.test_node, spend_tx, with_witness=False, accepted=False)
 
         # Try to put the witness script in the scriptSig, should also fail.
         spend_tx.vin[0].scriptSig = CScript([p2wsh_pubkey, b'a'])
         spend_tx.rehash()
         with self.nodes[0].assert_debug_log(
-                expected_msgs=(spend_tx.hash, 'was not accepted: mandatory-script-verify-flag-failed (Script evaluated without error but finished with a false/empty top stack element)')):
+                expected_msgs=[spend_tx.hash, 'was not accepted: mandatory-script-verify-flag-failed (Script evaluated without error but finished with a false/empty top stack element)']):
             test_transaction_acceptance(self.nodes[0], self.test_node, spend_tx, with_witness=False, accepted=False)
 
         # Now put the witness script in the witness, should succeed after

test/functional/p2p_v2_transport.py

@@ -145,7 +145,7 @@ def run_test(self):
         wrong_network_magic_prefix = MAGIC_BYTES["signet"] + V1_PREFIX[4:]
         with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
             s.connect(("127.0.0.1", p2p_port(0)))
-            with self.nodes[0].assert_debug_log("V2 transport error: V1 peer with wrong MessageStart"):
+            with self.nodes[0].assert_debug_log(["V2 transport error: V1 peer with wrong MessageStart"]):
                 s.sendall(wrong_network_magic_prefix + b"somepayload")
 
         # Check detection of missing garbage terminator (hits after fixed amount of data if terminator never matches garbage)
@@ -156,7 +156,7 @@ def run_test(self):
             self.wait_until(lambda: len(self.nodes[0].getpeerinfo()) == num_peers + 1)
             s.sendall(b'\x00' * (MAX_KEY_GARB_AND_GARBTERM_LEN - 1))
             self.wait_until(lambda: self.nodes[0].getpeerinfo()[-1]["bytesrecv"] == MAX_KEY_GARB_AND_GARBTERM_LEN - 1)
-            with self.nodes[0].assert_debug_log("V2 transport error: missing garbage terminator"):
+            with self.nodes[0].assert_debug_log(["V2 transport error: missing garbage terminator"]):
                 s.sendall(b'\x00')  # send out last byte
                 # should disconnect immediately
                 self.wait_until(lambda: len(self.nodes[0].getpeerinfo()) == num_peers)

test/functional/test_framework/test_node.py

@@ -448,6 +448,12 @@ def debug_log_size(self, **kwargs) -> int:
     def assert_debug_log(self, expected_msgs, unexpected_msgs=None, timeout=2):
         if unexpected_msgs is None:
             unexpected_msgs = []
+        # enforce that `{un}expected_msgs` are lists, in order to avoid bugs where strings
+        # are passed as arguments, which would be interpreted as lists of single characters
+        # (likely always passing the debug log assertion)
+        assert_equal(type(expected_msgs), list)
+        assert_equal(type(unexpected_msgs), list)
+
         time_end = time.time() + timeout * self.timeout_factor
         prev_size = self.debug_log_size(encoding="utf-8")  # Must use same encoding that is used to read() below