bitcoind: importmulti fails (bitcoin master), use importdescriptors

But this requires a watch-only wallet, and python-bitcoinlib doesn't support
multiple wallets, so we need to unload the original one, but then we need
to generate a block, so that can't generate a new address, so we need
an address arg to generate_block.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

contrib/pyln-testing/pyln/testing/utils.py

@@ -422,7 +422,7 @@ class BitcoinD(TailableProc):
     # int > 0 := wait for at least N transactions
     # 'tx_id' := wait for one transaction id given as a string
     # ['tx_id1', 'tx_id2'] := wait until all of the specified transaction IDs
-    def generate_block(self, numblocks=1, wait_for_mempool=0):
+    def generate_block(self, numblocks=1, wait_for_mempool=0, to_addr=None):
         if wait_for_mempool:
             if isinstance(wait_for_mempool, str):
                 wait_for_mempool = [wait_for_mempool]
@@ -439,7 +439,9 @@ class BitcoinD(TailableProc):
         ))
 
         # As of 0.16, generate() is removed; use generatetoaddress.
-        return self.rpc.generatetoaddress(numblocks, self.rpc.getnewaddress())
+        if to_addr is None:
+            to_addr = self.rpc.getnewaddress()
+        return self.rpc.generatetoaddress(numblocks, to_addr)
 
     def simple_reorg(self, height, shift=0):
         """

tests/test_wallet.py

@@ -1189,21 +1189,37 @@ def test_hsmtool_dump_descriptors(node_factory, bitcoind):
     out = subprocess.check_output(cmd_line).decode("utf8").split("\n")
     descriptor = [l for l in out if l.startswith("wpkh(tpub")][0]
 
+    # If we switch wallet, we can't generate address: do so now.
+    mine_to_addr = bitcoind.rpc.getnewaddress()
+
     # Import the descriptor to bitcoind
-    # FIXME: if we update the testsuite to use the upcoming 0.21 we could use
-    # importdescriptors instead.
-    bitcoind.rpc.importmulti([{
-        "desc": descriptor,
-        # No need to rescan, we'll transact afterward
-        "timestamp": "now",
-        # The default
-        "range": [0, 99]
-    }])
+    try:
+        bitcoind.rpc.importmulti([{
+            "desc": descriptor,
+            # No need to rescan, we'll transact afterward
+            "timestamp": "now",
+            # The default
+            "range": [0, 99]
+        }])
+    except JSONRPCError:
+        # Oh look, a new API!
+        # Need watch-only wallet, since descriptor has no privkeys.
+        bitcoind.rpc.createwallet("lightningd-ro", True)
+
+        # FIXME: No way to access non-default wallet in python-bitcoinlib
+        bitcoind.rpc.unloadwallet("lightningd-tests", True)
+        bitcoind.rpc.importdescriptors([{
+            "desc": descriptor,
+            # No need to rescan, we'll transact afterward
+            "timestamp": "now",
+            # The default
+            "range": [0, 99]
+        }])
 
     # Funds sent to lightningd can be retrieved by bitcoind
     addr = l1.rpc.newaddr()["bech32"]
     txid = l1.rpc.withdraw(addr, 10**3)["txid"]
-    bitcoind.generate_block(1, txid)
+    bitcoind.generate_block(1, txid, mine_to_addr)
     assert len(bitcoind.rpc.listunspent(1, 1, [addr])) == 1