Move external signer out of wallet module

This commit moves the ExternalSigner class and RPC methods out of the wallet module.

The enumeratesigners RPC can be used without a wallet since #21417.
With additional modifications external signers could be used without a wallet in general, e.g. via signrawtransaction.

The signerdisplayaddress RPC is ranamed to walletdisplayaddress because it requires wallet context.
A future displayaddress RPC call without wallet context could take a descriptor argument.

This commit fixes a rpc_help.py failure when configured with --disable-wallet.

test/functional/rpc_signer.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017-2018 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test external signer.
+
+Verify that a bitcoind node can use an external signer command.
+See also wallet_signer.py for tests that require wallet context.
+"""
+import os
+import platform
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+
+
+class RPCSignerTest(BitcoinTestFramework):
+    def mock_signer_path(self):
+        path = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'mocks', 'signer.py')
+        if platform.system() == "Windows":
+            return "py " + path
+        else:
+            return path
+
+    def set_test_params(self):
+        self.num_nodes = 4
+
+        self.extra_args = [
+            [],
+            [f"-signer={self.mock_signer_path()}", '-keypool=10'],
+            [f"-signer={self.mock_signer_path()}", '-keypool=10'],
+            ["-signer=fake.py"],
+        ]
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_external_signer()
+
+    def set_mock_result(self, node, res):
+        with open(os.path.join(node.cwd, "mock_result"), "w", encoding="utf8") as f:
+            f.write(res)
+
+    def clear_mock_result(self, node):
+        os.remove(os.path.join(node.cwd, "mock_result"))
+
+    def run_test(self):
+        self.log.debug(f"-signer={self.mock_signer_path()}")
+
+        assert_raises_rpc_error(-1, 'Error: restart bitcoind with -signer=<cmd>',
+            self.nodes[0].enumeratesigners
+        )
+
+        # Handle script missing:
+        assert_raises_rpc_error(-1, 'execve failed: No such file or directory',
+            self.nodes[3].enumeratesigners
+        )
+
+        # Handle error thrown by script
+        self.set_mock_result(self.nodes[1], "2")
+        assert_raises_rpc_error(-1, 'RunCommandParseJSON error',
+            self.nodes[1].enumeratesigners
+        )
+        self.clear_mock_result(self.nodes[1])
+
+        self.set_mock_result(self.nodes[1], '0 [{"type": "trezor", "model": "trezor_t", "error": "fingerprint not found"}]')
+        assert_raises_rpc_error(-1, 'fingerprint not found',
+            self.nodes[1].enumeratesigners
+        )
+        self.clear_mock_result(self.nodes[1])
+
+        result = self.nodes[1].enumeratesigners()
+        assert_equal(len(result['signers']), 2)
+        assert_equal(result['signers'][0]["fingerprint"], "00000001")
+        assert_equal(result['signers'][0]["name"], "trezor_t")
+
+if __name__ == '__main__':
+    RPCSignerTest().main()

test/functional/test_runner.py

@@ -111,6 +111,7 @@ BASE_SCRIPTS = [
     'wallet_listtransactions.py --legacy-wallet',
     'wallet_listtransactions.py --descriptors',
     'feature_taproot.py',
+    'rpc_signer.py',
     'wallet_signer.py --descriptors',
     # vv Tests less than 60s vv
     'p2p_sendheaders.py',

test/functional/wallet_signer.py

@@ -5,6 +5,7 @@
 """Test external signer.
 
 Verify that a bitcoind node can use an external signer command
+See also rpc_signer.py for tests without wallet context.
 """
 import os
 import platform
@@ -16,7 +17,7 @@ from test_framework.util import (
 )
 
 
-class SignerTest(BitcoinTestFramework):
+class WalletSignerTest(BitcoinTestFramework):
     def mock_signer_path(self):
         path = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'mocks', 'signer.py')
         if platform.system() == "Windows":
@@ -25,18 +26,16 @@ class SignerTest(BitcoinTestFramework):
             return path
 
     def set_test_params(self):
-        self.num_nodes = 4
+        self.num_nodes = 2
 
         self.extra_args = [
             [],
             [f"-signer={self.mock_signer_path()}", '-keypool=10'],
-            [f"-signer={self.mock_signer_path()}", '-keypool=10'],
-            ["-signer=fake.py"],
         ]
 
     def skip_test_if_missing_module(self):
-        self.skip_if_no_wallet()
         self.skip_if_no_external_signer()
+        self.skip_if_no_wallet()
 
     def set_mock_result(self, node, res):
         with open(os.path.join(node.cwd, "mock_result"), "w", encoding="utf8") as f:
@@ -48,28 +47,6 @@ class SignerTest(BitcoinTestFramework):
     def run_test(self):
         self.log.debug(f"-signer={self.mock_signer_path()}")
 
-        assert_raises_rpc_error(-4, 'Error: restart bitcoind with -signer=<cmd>',
-            self.nodes[0].enumeratesigners
-        )
-
-        # Handle script missing:
-        assert_raises_rpc_error(-1, 'execve failed: No such file or directory',
-            self.nodes[3].enumeratesigners
-        )
-
-        # Handle error thrown by script
-        self.set_mock_result(self.nodes[1], "2")
-        assert_raises_rpc_error(-1, 'RunCommandParseJSON error',
-            self.nodes[1].enumeratesigners
-        )
-        self.clear_mock_result(self.nodes[1])
-
-        self.set_mock_result(self.nodes[1], '0 [{"type": "trezor", "model": "trezor_t", "error": "fingerprint not found"}]')
-        assert_raises_rpc_error(-4, 'fingerprint not found',
-            self.nodes[1].enumeratesigners
-        )
-        self.clear_mock_result(self.nodes[1])
-
         # Create new wallets for an external signer.
         # disable_private_keys and descriptors must be true:
         assert_raises_rpc_error(-4, "Private keys must be disabled when using an external signer", self.nodes[1].createwallet, wallet_name='not_hww', disable_private_keys=False, descriptors=True, external_signer=True)
@@ -81,11 +58,6 @@ class SignerTest(BitcoinTestFramework):
         self.nodes[1].createwallet(wallet_name='hww', disable_private_keys=True, descriptors=True, external_signer=True)
         hww = self.nodes[1].get_wallet_rpc('hww')
 
-        result = hww.enumeratesigners()
-        assert_equal(len(result['signers']), 2)
-        assert_equal(result['signers'][0]["fingerprint"], "00000001")
-        assert_equal(result['signers'][0]["name"], "trezor_t")
-
         # Flag can't be set afterwards (could be added later for non-blank descriptor based watch-only wallets)
         self.nodes[1].createwallet(wallet_name='not_hww', disable_private_keys=True, descriptors=True, external_signer=False)
         not_hww = self.nodes[1].get_wallet_rpc('not_hww')
@@ -123,14 +95,14 @@ class SignerTest(BitcoinTestFramework):
         assert_equal(address_info['ismine'], True)
         assert_equal(address_info['hdkeypath'], "m/44'/1'/0'/0/0")
 
-        self.log.info('Test signerdisplayaddress')
-        result = hww.signerdisplayaddress(address1)
+        self.log.info('Test walletdisplayaddress')
+        result = hww.walletdisplayaddress(address1)
         assert_equal(result, {"address": address1})
 
         # Handle error thrown by script
         self.set_mock_result(self.nodes[1], "2")
         assert_raises_rpc_error(-1, 'RunCommandParseJSON error',
-            hww.signerdisplayaddress, address1
+            hww.walletdisplayaddress, address1
         )
         self.clear_mock_result(self.nodes[1])
 
@@ -214,4 +186,4 @@ class SignerTest(BitcoinTestFramework):
         # self.clear_mock_result(self.nodes[4])
 
 if __name__ == '__main__':
-    SignerTest().main()
+    WalletSignerTest().main()