Reset client_state toi_mode to m_undefined after RSU

Client state end_rsu() didn't reset toi_mode to m_undefined,
which caused an assertion when NBO was started after RSU.

As a fix, reset toi_mode to m_undefined in end_rsu() after
changing mode.

src/client_state.cpp

@@ -554,6 +554,7 @@ int wsrep::client_state::end_rsu()
     }
     wsrep::unique_lock<wsrep::mutex> lock(mutex_);
     mode(lock, toi_mode_);
+    toi_mode_ = m_undefined;
     return ret;
 }
 

test/CMakeLists.txt

@@ -11,6 +11,7 @@ add_executable(wsrep-lib_test
   gtid_test.cpp
   id_test.cpp
   nbo_test.cpp
+  rsu_test.cpp
   server_context_test.cpp
   toi_test.cpp
   transaction_test.cpp

test/rsu_test.cpp

@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2021 Codership Oy <info@codership.com>
+ *
+ * This file is part of wsrep-lib.
+ *
+ * Wsrep-lib is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Wsrep-lib is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wsrep-lib.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "wsrep/client_state.hpp"
+
+#include "client_state_fixture.hpp"
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_CASE(test_rsu,
+                        replicating_client_fixture_sync_rm)
+{
+    BOOST_REQUIRE(cc.begin_rsu(1) == 0);
+    BOOST_REQUIRE(cc.mode() == wsrep::client_state::m_rsu);
+    BOOST_REQUIRE(cc.toi_mode() == wsrep::client_state::m_local);
+
+    BOOST_REQUIRE(cc.end_rsu() == 0);
+    BOOST_REQUIRE(cc.mode() == wsrep::client_state::m_local);
+    BOOST_REQUIRE(cc.toi_mode() == wsrep::client_state::m_undefined);
+}