MXS-1743: Expand test case to cover load balancing

The test case now verifies that the servers are actually load balanced
correctly. This test reveals a problem in the readconnroute; the master is
always preferred over slaves if one is available with
router_options=master,slave.

maxscale-system-test/mxs1743_rconn_bitmask.cpp

@@ -4,12 +4,12 @@
  * https://jira.mariadb.org/browse/MXS-1743
  */
 #include "testconnections.h"
+#include <vector>
 
 int main(int argc, char** argv)
 {
     TestConnections test(argc, argv);
 
-
     test.tprintf("Testing with both master and slave up");
     test.maxscales->connect();
     test.try_query(test.maxscales->conn_master[0], "SELECT 1");
@@ -31,6 +31,44 @@ int main(int argc, char** argv)
     test.try_query(test.maxscales->conn_master[0], "SELECT 1");
     test.maxscales->disconnect();
     test.repl->unblock_node(1);
+    sleep(5);
+
+    test.tprintf("Checking that both the master and slave are used");
+    std::vector<MYSQL*> connections;
+
+    test.repl->connect();
+    execute_query_silent(test.repl->nodes[0], "DROP USER IF EXISTS 'mxs1743'@'%'");
+    test.try_query(test.repl->nodes[0], "%s", "CREATE USER 'mxs1743'@'%' IDENTIFIED BY 'mxs1743'");
+    test.try_query(test.repl->nodes[0], "%s", "GRANT ALL ON *.* TO 'mxs1743'@'%'");
+    test.repl->sync_slaves();
+
+    for (int i = 0; i < 20; i++)
+    {
+        connections.push_back(open_conn(test.maxscales->readconn_master_port[0],
+                                        test.maxscales->IP[0], "mxs1743",
+                                        "mxs1743", false));
+    }
+
+    // Give the connections a few seconds to establish
+    sleep(5);
+
+    std::string query = "SELECT COUNT(*) AS connections FROM information_schema.processlist WHERE user = 'mxs1743'";
+    char master_connections[1024];
+    char slave_connections[1024];
+    find_field(test.repl->nodes[0], query.c_str(), "connections", master_connections);
+    find_field(test.repl->nodes[1], query.c_str(), "connections", slave_connections);
+
+    test.assert(strcmp(master_connections, slave_connections) == 0,
+                "Master and slave shoud have the same amount of connections: %s != %s",
+                master_connections, slave_connections);
+
+    for (auto a: connections)
+    {
+        mysql_close(a);
+    }
+
+    execute_query_silent(test.repl->nodes[0], "DROP USER 'mxs1743'@'%'");
+    test.repl->disconnect();
 
     return test.global_result;
 }