test: disallow sendtoaddress/sendmany when private keys disabled

Author: jonatack

Diff for: test/functional/wallet_watchonly.py

@@ -2,7 +2,7 @@
 # Copyright (c) 2018-2019 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 createwallet arguments.
+"""Test createwallet watchonly arguments.
 """
 
 from test_framework.test_framework import BitcoinTestFramework
@@ -49,6 +49,11 @@ def run_test(self):
         assert_equal(len(wo_wallet.listtransactions()), 1)
         assert_equal(wo_wallet.getbalance(include_watchonly=False), 0)
 
+        self.log.info('Test sending from a watch-only wallet raises RPC error')
+        msg = "Error: Private keys are disabled for this wallet"
+        assert_raises_rpc_error(-4, msg, wo_wallet.sendtoaddress, a1, 0.1)
+        assert_raises_rpc_error(-4, msg, wo_wallet.sendmany, amounts={a1: 0.1})
+
         self.log.info('Testing listreceivedbyaddress watch-only defaults')
         result = wo_wallet.listreceivedbyaddress()
         assert_equal(len(result), 1)