MXS-1889 Add test

If all slaves are down, a connection should be created to the
master.

maxscale-system-test/CMakeLists.txt

@@ -922,6 +922,10 @@ add_test_executable(mxs1628_bad_handshake.cpp mxs1628_bad_handshake replication
 # MXS-1836: MaxInfo "show eventTimes" returns garbage.
 add_test_executable(mxs1836_show_eventTimes.cpp mxs1836_show_eventTimes mxs1836_show_eventTimes LABELS REPL_BACKEND)
 
+ # MXS-1889: A single remaining master is valid for readconnroute configured with 'router_options=slave'
+ # https://jira.mariadb.org/browse/MXS-1889
+add_test_executable(mxs1889.cpp mxs1889 mxs1889 LABELS REPL_BACKEND)
+
 configure_file(templates.h.in templates.h @ONLY)
 
 include(CTest)

maxscale-system-test/cnf/maxscale.cnf.template.mxs1889

@@ -0,0 +1,89 @@
+[maxscale]
+threads=###threads###
+log_info=on
+
+[MySQL Monitor]
+type=monitor
+module=mysqlmon
+###repl51###
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+monitor_interval=1000
+
+[RW Split Router]
+type=service
+router=readwritesplit
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+router_options=slave_selection_criteria=LEAST_GLOBAL_CONNECTIONS
+max_slave_connections=1
+
+[Read Connection Router Slave]
+type=service
+router=readconnroute
+router_options=slave
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+
+[Read Connection Router Master]
+type=service
+router=readconnroute
+router_options=master
+servers=server1,server2,server3,server4
+user=maxskysql
+passwd=skysql
+
+[RW Split Listener]
+type=listener
+service=RW Split Router
+protocol=MySQLClient
+port=4006
+
+[Read Connection Listener Slave]
+type=listener
+service=Read Connection Router Slave
+protocol=MySQLClient
+port=4009
+
+[Read Connection Listener Master]
+type=listener
+service=Read Connection Router Master
+protocol=MySQLClient
+port=4008
+
+[CLI]
+type=service
+router=cli
+
+[CLI Listener]
+type=listener
+service=CLI
+protocol=maxscaled
+socket=default
+
+[server1]
+type=server
+address=###node_server_IP_1###
+port=###node_server_port_1###
+protocol=MySQLBackend
+
+[server2]
+type=server
+address=###node_server_IP_2###
+port=###node_server_port_2###
+protocol=MySQLBackend
+
+[server3]
+type=server
+address=###node_server_IP_3###
+port=###node_server_port_3###
+protocol=MySQLBackend
+
+[server4]
+type=server
+address=###node_server_IP_4###
+port=###node_server_port_4###
+protocol=MySQLBackend

maxscale-system-test/mxs1889.cpp

@@ -0,0 +1,36 @@
+/**
+ * MXS-1889: A single remaining master is valid for readconnroute configured with 'router_options=slave'
+ *
+ * https://jira.mariadb.org/browse/MXS-1889
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+
+    // Give some time for things to stabilize.
+    sleep(2);
+
+    // Take down all slaves.
+    test.repl->stop_node(1);
+    test.repl->stop_node(2);
+    test.repl->stop_node(3);
+
+    // Give the monitor some time to detect it
+    sleep(5);
+
+    test.maxscales->connect();
+
+    // Should succeed.
+    test.try_query(test.maxscales->conn_slave[0], "SELECT 1");
+
+    int rv = test.global_result;
+
+    test.repl->start_node(3);
+    test.repl->start_node(2);
+    test.repl->start_node(1);
+
+    return rv;
+}