# 
# BUG
# ---
#   BUG#28796: CHANGE MASTER TO MASTER_HOST="" leads to invalid master.info
#
# Description
# -----------
#
#   This test aims at: 
#     i) verifying that an error is thrown when setting MASTER_HOST=''
#     ii) no error is thrown when setting non empty MASTER_HOST
#     iii) replication works after setting a correct host name/ip
#
#   Implementation is performed by feeding different values (according
#   to i), ii) and iii) ) to CHANGE MASTER TO MASTER_HOST= x and checking
#   along the way if error/no error is thrown and/or if replication starts
#   working when expected.

--source include/have_binlog_format_mixed.inc
--source include/master-slave.inc

connection slave;
STOP SLAVE;
--source include/wait_for_slave_to_stop.inc

let $master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1);
--echo Master_Host = '$master_host' (expected '127.0.0.1')

# attempt to change to an empty master host should 
# result in error ER_WRONG_ARGUMENTS: "Incorrect arguments to ..."
error ER_WRONG_ARGUMENTS;
CHANGE MASTER TO MASTER_HOST="";

# show slave status still holds previous information
let $master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1);
--echo Master_Host = '$master_host' (expected '127.0.0.1')

# changing master to other than empty master host succeeds
CHANGE MASTER TO MASTER_HOST="foo";

# show slave status should hold "foo" as master host
let $master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1);
--echo Master_Host = '$master_host' (expected 'foo')

# changing back to localhost
CHANGE MASTER TO MASTER_HOST="127.0.0.1";
let $master_host= query_get_value(SHOW SLAVE STATUS, Master_Host, 1);
--echo Master_Host = '$master_host' (expected '127.0.0.1')

# start slave must succeed.
START SLAVE;
--source include/wait_for_slave_to_start.inc
--source include/rpl_end.inc