MXS-359: Add master switch test case

The test case verifies that the router behaves in the expected manner with
regards to transaction state and type, autocommit state and statement
type.

maxscale-system-test/mxs359_master_switch.cpp

@@ -0,0 +1,87 @@
+/**
+ * MXS-359: Switch master mid-session
+ *
+ * https://jira.mariadb.org/browse/MXS-359
+ */
+#include "testconnections.h"
+
+TestConnections* global_test;
+
+void change_master(int next, int current)
+{
+    TestConnections& test = *global_test;
+    test.repl->connect();
+    test.repl->change_master(current, next);
+    test.repl->close_connections();
+}
+
+struct Test
+{
+    const char* query;
+    bool        should_work;
+
+    Test(const char* q = NULL, bool works = true):
+        query(q),
+        should_work(works)
+    {
+    }
+};
+
+void do_test(Test pre, Test post)
+{
+    TestConnections& test = *global_test;
+    int rc;
+    test.maxscales->connect();
+
+    if (pre.query)
+    {
+        rc = execute_query_silent(test.maxscales->conn_rwsplit[0], pre.query);
+        test.assert((rc == 0) == pre.should_work, "Expected query '%s' to %s: %s",
+                    pre.query, pre.should_work ? "succeed" : "fail",
+                    mysql_error(test.maxscales->conn_rwsplit[0]));
+    }
+
+    change_master(1, 0);
+    sleep(5);
+
+    rc = execute_query_silent(test.maxscales->conn_rwsplit[0], post.query);
+    test.assert((rc == 0) == post.should_work, "Expected query '%s' to %s: %s",
+                post.query, post.should_work ? "succeed" : "fail",
+                mysql_error(test.maxscales->conn_rwsplit[0]));
+
+    change_master(0, 1);
+    test.maxscales->disconnect();
+
+    sleep(5);
+}
+
+int main(int argc, char** argv)
+{
+    TestConnections test(argc, argv);
+    global_test = &test;
+
+    // Prepare a table for testing
+    test.maxscales->connect();
+    test.try_query(test.maxscales->conn_rwsplit[0], "CREATE OR REPLACE TABLE test.t1(id INT)");
+    test.repl->sync_slaves();
+    test.maxscales->disconnect();
+
+    test.tprintf("Check that write after change works");
+    do_test({}, {"INSERT INTO test.t1 VALUES (1)"});
+
+    test.tprintf("Check that write with open transaction fails");
+    do_test({"START TRANSACTION"}, {"INSERT INTO test.t1 VALUES (1)", false});
+
+    test.tprintf("Check that read with open read-only transaction works");
+    do_test({"START TRANSACTION READ ONLY"}, {"SELECT 1"});
+
+    test.tprintf("Check that write with autocommit=0 fails");
+    do_test({"SET autocommit=0"}, {"INSERT INTO test.t1 VALUES (1)", false});
+
+    test.maxscales->connect();
+    test.try_query(test.maxscales->conn_rwsplit[0], "DROP TABLE test.t1");
+    test.repl->fix_replication();
+    test.maxscales->disconnect();
+
+    return test.global_result;
+}