test: blank rpcauth CLI interaction

Tests interactions between blank and
non-blank rpcauth args.

Author: tdb3

test/functional/rpc_users.py

@@ -150,6 +150,15 @@ def run_test(self):
         self.nodes[0].assert_start_raises_init_error(expected_msg=init_error, extra_args=['-rpcauth=foo$bar:baz'])
         self.nodes[0].assert_start_raises_init_error(expected_msg=init_error, extra_args=['-rpcauth=foo$bar$baz'])
 
+        self.log.info('Check interactions between blank and non-blank rpcauth')
+        # pw = bitcoin
+        rpcauth_user1 = '-rpcauth=user1:6dd184e5e69271fdd69103464630014f$eb3d7ce67c4d1ff3564270519b03b636c0291012692a5fa3dd1d2075daedd07b'
+        rpcauth_user2 = '-rpcauth=user2:57b2f77c919eece63cfa46c2f06e46ae$266b63902f99f97eeaab882d4a87f8667ab84435c3799f2ce042ef5a994d620b'
+        self.restart_node(0, extra_args=[rpcauth_user1, rpcauth_user2, '-rpcauth=']) # fixed in subsequent commit
+        self.stop_node(0)
+        self.nodes[0].assert_start_raises_init_error(expected_msg=init_error, extra_args=[rpcauth_user1, '-rpcauth=', rpcauth_user2])
+        self.nodes[0].assert_start_raises_init_error(expected_msg=init_error, extra_args=['-rpcauth=', rpcauth_user1, rpcauth_user2])
+
         self.log.info('Check that failure to write cookie file will abort the node gracefully')
         (self.nodes[0].chain_path / ".cookie.tmp").mkdir()
         self.nodes[0].assert_start_raises_init_error(expected_msg=init_error)