[QA] add fundrawtransaction test on a locked wallet with empty keypool

qa/rpc-tests/fundrawtransaction.py

@@ -536,7 +536,23 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.is_network_split=False
         self.sync_all()
 
-        error = False
+        # drain the keypool
+        self.nodes[1].getnewaddress()
+        inputs = []
+        outputs = {self.nodes[0].getnewaddress():1.1}
+        rawTx = self.nodes[1].createrawtransaction(inputs, outputs)
+        # fund a transaction that requires a new key for the change output
+        # creating the key must be impossible because the wallet is locked
+        try:
+            fundedTx = self.nodes[1].fundrawtransaction(rawTx)
+            raise AssertionError("Wallet unlocked without passphrase")
+        except JSONRPCException as e:
+            assert('Keypool ran out' in e.error['message'])
+
+        #refill the keypool
+        self.nodes[1].walletpassphrase("test", 100)
+        self.nodes[1].walletlock()
+
         try:
             self.nodes[1].sendtoaddress(self.nodes[0].getnewaddress(), 1.2)
         except: