From d8a39c4459682e60a3c6dbd18b301678cb520caf Mon Sep 17 00:00:00 2001
From: Ferdinando Ametrano <ferdinando@ametrano.net>
Date: Mon, 7 Sep 2026 20:42:48 +0200
Subject: [PATCH] descriptor: fix two parse-error messages and cover them with
 tests

The bare-multisig error prints a literal "{}" because its .format() call
is missing. The wpkh branch reports "More than one pubkey in pkh
descriptor", copied from the pkh branch.

Add unit tests for both error paths: a wpkh() with two pubkeys, and a
top-level bare multisig with four pubkeys whose message must report the
count.
---
 hwilib/descriptor.py    |  4 ++--
 test/test_descriptor.py | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/hwilib/descriptor.py b/hwilib/descriptor.py
index 1373ad2d2..04aa7e4a7 100644
--- a/hwilib/descriptor.py
+++ b/hwilib/descriptor.py
@@ -673,14 +673,14 @@ def _parse_descriptor(desc: str, ctx: '_ParseDescriptorContext', key_expr_index:
         elif thresh > len(pubkeys):
             raise ValueError("Multisig threshold cannot be larger than the number of keys; threshold is {} but only {} keys specified".format(thresh, len(pubkeys)))
         if ctx == _ParseDescriptorContext.TOP and len(pubkeys) > 3:
-            raise ValueError("Cannot have {} pubkeys in bare multisig: only at most 3 pubkeys")
+            raise ValueError("Cannot have {} pubkeys in bare multisig: only at most 3 pubkeys".format(len(pubkeys)))
         return MultisigDescriptor(pubkeys, thresh, is_sorted), key_expr_index
     if func == "wpkh":
         if not (ctx == _ParseDescriptorContext.TOP or ctx == _ParseDescriptorContext.P2SH):
             raise ValueError("Can only have wpkh() at top level or inside sh()")
         pubkey, expr, key_expr_index = parse_pubkey(expr, key_expr_index)
         if expr:
-            raise ValueError("More than one pubkey in pkh descriptor")
+            raise ValueError("More than one pubkey in wpkh descriptor")
         return WPKHDescriptor(pubkey), key_expr_index
     if func == "sh":
         if ctx != _ParseDescriptorContext.TOP:
diff --git a/test/test_descriptor.py b/test/test_descriptor.py
index dca4fbe80..a57111742 100755
--- a/test/test_descriptor.py
+++ b/test/test_descriptor.py
@@ -294,6 +294,20 @@ def test_invalid_multipath_descriptors(self):
         with self.assertRaisesRegex(ValueError, "invalid literal for int()"):
             parse_descriptor("wpkh(xpub661MyMwAqRbcFW31YEwpkMuc5THy2PSt5bDMsktWQcFF8syAmRUapSCGu8ED9W6oDMSgv6Zz8idoc4a6mr8BDzTJY47LJhkJ8UB7WEGuduB/<0;>/*)")
 
+    def test_wpkh_rejects_multiple_pubkeys(self):
+        pk1 = "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798"
+        pk2 = "02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5"
+        with self.assertRaisesRegex(ValueError, "More than one pubkey in wpkh descriptor"):
+            parse_descriptor("wpkh({},{})".format(pk1, pk2))
+
+    def test_bare_multisig_too_many_pubkeys_reports_count(self):
+        pk1 = "0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798"
+        pk2 = "02c6047f9441ed7d6d3045406e95c07cd85c778e4b8cef3ca7abac09b95c709ee5"
+        pk3 = "02f9308a019258c31049344f85f89d5229b531c845836f99b08601f113bce036f9"
+        pk4 = "02e493dbf1c10d80f3581e4904930b1404cc6c13900ee0758474fa94abe8c4cd13"
+        with self.assertRaisesRegex(ValueError, "Cannot have 4 pubkeys in bare multisig: only at most 3 pubkeys"):
+            parse_descriptor("multi(1,{},{},{},{})".format(pk1, pk2, pk3, pk4))
+
     def test_valid_bip388_conversion(self):
         def check(descriptor, keys, template):
             d = parse_descriptor(descriptor)