Merge #20226: wallet, rpc: add listdescriptors command

647b81b709 wallet, rpc: add listdescriptors command (Ivan Metlushko)

Pull request description:

  Looking for concept ACKs

  **Rationale**: allow users to inspect the contents of their newly created descriptor wallets.

  Currently the command only returns xpubs which is not very useful in itself, but there are multiples ways to extend it:
   * add an option to export xprv
   * with #19136 it'll be possible to return normalised descriptors suitable for a watch-only purposes

  The output is compatible with `importdescriptors` command so it could be easily used for backup/recover purposes.

  **Output example:**
  ```json
  [
    {
      "desc": "wpkh(tpubD6NzVbkrYhZ4WW6E2ZETFyNfq2hfF23SKxqSGFvUpPAY58jmmuBybwqwFihAyQPk9KnwTt5516NDZRJ7k5QPeKjy7wuVd5WvXNxwwAs5tUD/*)#nhavpr5h",
      "timestamp": 1296688602,
      "active": false,
      "range": [
        0,
        999
      ],
      "next": 0
    }
  ]
  ```

ACKs for top commit:
  jonatack:
    re-ACK 647b81b709 rebased to master, debug builds cleanly, reviewed diff since last review, tested with a descriptor wallet (and with a legacy wallet)
  achow101:
    re-ACK 647b81b

Tree-SHA512: 51a3620bb17c836c52cecb066d4fa9d5ff418af56809046eaee0528c4dc240a4e90fff5711ba96e399c6664e00b9ee8194e33852b1b9e75af18061296e19a8a7

test/functional/test_runner.py

@@ -238,6 +238,7 @@ BASE_SCRIPTS = [
     'rpc_named_arguments.py',
     'wallet_listsinceblock.py',
     'wallet_listsinceblock.py --descriptors',
+    'wallet_listdescriptors.py --descriptors',
     'p2p_leak.py',
     'wallet_encryption.py',
     'wallet_encryption.py --descriptors',

test/functional/wallet_listdescriptors.py

@@ -0,0 +1,67 @@
+#!/usr/bin/env python3
+# Copyright (c) 2014-2021 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 the listdescriptors RPC."""
+
+from test_framework.descriptors import (
+    descsum_create
+)
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+    assert_raises_rpc_error,
+)
+
+
+class ListDescriptorsTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+        self.skip_if_no_sqlite()
+
+    # do not create any wallet by default
+    def init_wallet(self, i):
+        return
+
+    def run_test(self):
+        node = self.nodes[0]
+        assert_raises_rpc_error(-18, 'No wallet is loaded.', node.listdescriptors)
+
+        self.log.info('Test that the command is not available for legacy wallets.')
+        node.createwallet(wallet_name='w1', descriptors=False)
+        assert_raises_rpc_error(-4, 'listdescriptors is not available for non-descriptor wallets', node.listdescriptors)
+
+        self.log.info('Test the command for empty descriptors wallet.')
+        node.createwallet(wallet_name='w2', blank=True, descriptors=True)
+        assert_equal(0, len(node.get_wallet_rpc('w2').listdescriptors()))
+
+        self.log.info('Test the command for a default descriptors wallet.')
+        node.createwallet(wallet_name='w3', descriptors=True)
+        result = node.get_wallet_rpc('w3').listdescriptors()
+        assert_equal(6, len(result))
+        assert_equal(6, len([d for d in result if d['active']]))
+        assert_equal(3, len([d for d in result if d['internal']]))
+        for item in result:
+            assert item['desc'] != ''
+            assert item['next'] == 0
+            assert item['range'] == [0, 0]
+            assert item['timestamp'] is not None
+
+        self.log.info('Test non-active non-range combo descriptor')
+        node.createwallet(wallet_name='w4', blank=True, descriptors=True)
+        wallet = node.get_wallet_rpc('w4')
+        wallet.importdescriptors([{
+            'desc': descsum_create('combo(' + node.get_deterministic_priv_key().key + ')'),
+            'timestamp': 1296688602,
+        }])
+        expected = [{'active': False,
+                     'desc': 'combo(0227d85ba011276cf25b51df6a188b75e604b38770a462b2d0e9fb2fc839ef5d3f)#np574htj',
+                     'timestamp': 1296688602}]
+        assert_equal(expected, wallet.listdescriptors())
+
+
+if __name__ == '__main__':
+    ListDescriptorsTest().main()