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

Two recently added tests (PR #28625 / commit 2e31250027
and PR #28634 / commit 3bb51c29df)
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.

test/functional/p2p_segwit.py

@@ -706,14 +706,14 @@ class SegWitTest(BitcoinTestFramework):
         # 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 @@ class V2TransportTest(BitcoinTestFramework):
         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 @@ class V2TransportTest(BitcoinTestFramework):
             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 +448,9 @@ class TestNode():
     def assert_debug_log(self, expected_msgs, unexpected_msgs=None, timeout=2):
         if unexpected_msgs is None:
             unexpected_msgs = []
+        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