MXS-1889 Improve test program

Verify that once there are slaves, we are connected
to a slave as expected.

maxscale-system-test/mxs1889.cpp

@@ -5,32 +5,81 @@
  */
 
 #include "testconnections.h"
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+namespace
+{
+
+string get_server_id(TestConnections& test, MYSQL* pMysql)
+{
+    string id;
+
+    int rv = mysql_query(pMysql, "SELECT @@server_id");
+    test.add_result(rv, "Could not execute query.");
+
+    if (rv == 0)
+    {
+        MYSQL_RES* pResult = mysql_store_result(pMysql);
+        test.assert(pResult, "Could not store result.");
+
+        if (pResult)
+        {
+            unsigned int n = mysql_field_count(pMysql);
+            test.assert(n == 1, "Unexpected number of fields.");
+
+            MYSQL_ROW pzRow = mysql_fetch_row(pResult);
+            test.assert(pzRow, "Returned row was NULL.");
+
+            if (pzRow)
+            {
+                id = pzRow[0];
+            }
+
+            mysql_free_result(pResult);
+        }
+    }
+
+    return id;
+}
+
+}
 
 int main(int argc, char** argv)
 {
     TestConnections test(argc, argv);
 
-    // Give some time for things to stabilize.
-    sleep(2);
-
-    // Take down all slaves.
+    test.tprintf("Taking 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
+    test.tprintf("Giving monitor time to detect the situation...");
     sleep(5);
 
     test.maxscales->connect();
 
-    // Should succeed.
-    test.try_query(test.maxscales->conn_slave[0], "SELECT 1");
+    // All slaves down, so we expect a connection to the master.
+    string master_id = get_server_id(test, test.maxscales->conn_slave[0]);
+    test.tprintf("Master id: %s", master_id.c_str());
 
-    int rv = test.global_result;
+    test.maxscales->disconnect();
 
+    test.tprintf("Starting all slaves.");
     test.repl->start_node(3);
     test.repl->start_node(2);
     test.repl->start_node(1);
 
-    return rv;
+    test.tprintf("Giving monitor time to detect the situation...");
+    sleep(5);
+
+    test.maxscales->connect();
+
+    string slave_id = get_server_id(test, test.maxscales->conn_slave[0]);
+    test.tprintf("Server id: %s", slave_id.c_str());
+    test.assert(slave_id != master_id, "Expected something else but %s", master_id.c_str());
+
+    return test.global_result;
 }