test: Run downgrade test on descriptor wallets

test/functional/wallet_backwards_compatibility.py

@@ -135,7 +135,9 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
         node_v17 = self.nodes[self.num_nodes - 2]
         node_v16 = self.nodes[self.num_nodes - 1]
 
-        legacy_nodes = self.nodes[2:]
+        legacy_nodes = self.nodes[2:] # Nodes that support legacy wallets
+        legacy_only_nodes = self.nodes[-5:] # Nodes that only support legacy wallets
+        descriptors_nodes = self.nodes[2:-5] # Nodes that support descriptor wallets
 
         self.generatetoaddress(node_miner, COINBASE_MATURITY + 1, node_miner.getnewaddress())
 
@@ -209,17 +211,21 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
 
         self.test_v19_addmultisigaddress()
 
-        if not self.options.descriptors:
+        self.log.info("Test that a wallet made on master can be opened on:")
-            # Descriptor wallets break compatibility, only run this test for legacy wallet
+        # In descriptors wallet mode, run this test on the nodes that support descriptor wallets
-            # Load modern wallet with older nodes
+        # In legacy wallets mode, run this test on the nodes that support legacy wallets
-            for node in legacy_nodes:
+        for node in descriptors_nodes if self.options.descriptors else legacy_nodes:
-                for wallet_name in ["w1", "w2", "w3"]:
+            if self.major_version_less_than(node, 17):
-                    if node.version < 170000:
                 # loadwallet was introduced in v0.17.0
                 continue
-                    if node.version < 180000 and wallet_name == "w3":
+            self.log.info(f"- {node.version}")
+            for wallet_name in ["w1", "w2", "w3"]:
+                if self.major_version_less_than(node, 18) and wallet_name == "w3":
                     # Blank wallets were introduced in v0.18.0. We test the loading error below.
                     continue
+                if self.major_version_less_than(node, 22) and wallet_name == "w1" and self.options.descriptors:
+                    # Descriptor wallets created after 0.21 have taproot descriptors which 0.21 does not support, tested below
+                    continue
                 node.loadwallet(wallet_name)
                 wallet = node.get_wallet_rpc(wallet_name)
                 info = wallet.getwalletinfo()
@@ -244,17 +250,21 @@ class BackwardsCompatibilityTest(BitcoinTestFramework):
                 else:
                     assert info['private_keys_enabled'] == True
                     assert info['keypoolsize'] == 0
-        else:
-            for node in legacy_nodes:
-                # Descriptor wallets appear to be corrupted wallets to old software
-                # and loadwallet is introduced in v0.17.0
-                if node.version >= 170000 and node.version < 210000:
-                    for wallet_name in ["w1", "w2", "w3"]:
-                        assert_raises_rpc_error(-4, "Wallet file verification failed: wallet.dat corrupt, salvage failed", node.loadwallet, wallet_name)
 
-        # RPC loadwallet failure causes bitcoind to exit, in addition to the RPC
+        # Check that descriptor wallets don't work on legacy only nodes
+        if self.options.descriptors:
+            self.log.info("Test descriptor wallet incompatibility on:")
+            for node in legacy_only_nodes:
+                # RPC loadwallet failure causes bitcoind to exit in <= 0.17, in addition to the RPC
                 # call failure, so the following test won't work:
                 # assert_raises_rpc_error(-4, "Wallet loading failed.", node_v17.loadwallet, 'w3')
+                if self.major_version_less_than(node, 18):
+                    continue
+                self.log.info(f"- {node.version}")
+                # Descriptor wallets appear to be corrupted wallets to old software
+                assert self.major_version_at_least(node, 18) and self.major_version_less_than(node, 21)
+                for wallet_name in ["w1", "w2", "w3"]:
+                    assert_raises_rpc_error(-4, "Wallet file verification failed: wallet.dat corrupt, salvage failed", node.loadwallet, wallet_name)
 
         # Instead, we stop node and try to launch it with the wallet:
         self.stop_node(node_v17.index)