diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 74dbc94..d2dc08c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -11,6 +11,7 @@ add_executable(wsrep-lib_test
   gtid_test.cpp
   id_test.cpp
   server_context_test.cpp
+  toi_test.cpp
   transaction_test.cpp
   transaction_test_2pc.cpp
   transaction_test_xa.cpp
diff --git a/test/mock_provider.hpp b/test/mock_provider.hpp
index 2146426..7f1e403 100644
--- a/test/mock_provider.hpp
+++ b/test/mock_provider.hpp
@@ -80,12 +80,11 @@ namespace wsrep
             WSREP_OVERRIDE
         {
             ws_handle = wsrep::ws_handle(ws_handle.transaction_id(), (void*)1);
-            wsrep::log_info() << "provider certify: "
-                              << "client: " << client_id.get()
-                              << " flags: " << std::hex << flags
-                              << std::dec
-                              << " certify_status: " << certify_result_;
-
+            wsrep::log_debug() << "provider certify: "
+                               << "client: " << client_id.get()
+                               << " flags: " << std::hex << flags
+                               << std::dec
+                               << " certify_status: " << certify_result_;
             if (certify_result_)
             {
                 return certify_result_;
@@ -235,13 +234,26 @@ namespace wsrep
             return wsrep::provider::success;
         }
 
-        enum wsrep::provider::status enter_toi(wsrep::client_id,
+        enum wsrep::provider::status enter_toi(wsrep::client_id client_id,
                                                const wsrep::key_array&,
                                                const wsrep::const_buffer&,
-                                               wsrep::ws_meta&,
+                                               wsrep::ws_meta& toi_meta,
                                                int)
             WSREP_OVERRIDE
-        { return wsrep::provider::success; }
+        {
+                ++group_seqno_;
+                wsrep::gtid gtid(group_id_, wsrep::seqno(group_seqno_));
+                wsrep::stid stid(server_id_,
+                                 wsrep::transaction_id::undefined(),
+                                 client_id);
+                toi_meta = wsrep::ws_meta(gtid, stid,
+                                          wsrep::seqno(group_seqno_ - 1),
+                                          wsrep::provider::flag::start_transaction |
+                                          wsrep::provider::flag::commit);
+
+            return wsrep::provider::success;
+        }
+
         enum wsrep::provider::status leave_toi(wsrep::client_id,
                                                const wsrep::mutable_buffer&)
             WSREP_OVERRIDE
diff --git a/test/toi_test.cpp b/test/toi_test.cpp
new file mode 100644
index 0000000..7d6d653
--- /dev/null
+++ b/test/toi_test.cpp
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2019 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_toi_mode,
+                        replicating_client_fixture_sync_rm)
+{
+    BOOST_REQUIRE(cc.mode() == wsrep::client_state::m_local);
+    wsrep::key key(wsrep::key::exclusive);
+    key.append_key_part("k1", 2);
+    key.append_key_part("k2", 2);
+    wsrep::key_array keys{key};
+    wsrep::const_buffer buf("toi", 3);
+    BOOST_REQUIRE(cc.enter_toi(keys, buf,
+                               wsrep::provider::flag::start_transaction |
+                               wsrep::provider::flag::commit) == 0);
+    BOOST_REQUIRE(cc.mode() == wsrep::client_state::m_toi);
+    BOOST_REQUIRE(cc.in_toi());
+    BOOST_REQUIRE(cc.toi_mode() == wsrep::client_state::m_local);
+    BOOST_REQUIRE(cc.leave_toi() == 0);
+    BOOST_REQUIRE(cc.mode() == wsrep::client_state::m_local);
+}
+
+BOOST_FIXTURE_TEST_CASE(test_toi_applying,
+                        applying_client_fixture)
+{
+    // Fixture opens a transaction, commit it first
+    BOOST_REQUIRE((cc.before_commit() || cc.ordered_commit() ||
+                   cc.after_commit()) == 0);
+    cc.after_applying();
+
+    wsrep::ws_meta ws_meta(wsrep::gtid(wsrep::id("1"), wsrep::seqno(2)),
+                           wsrep::stid(sc.id(),
+                                       wsrep::transaction_id::undefined(),
+                                       cc.id()),
+                           wsrep::seqno(1),
+                           wsrep::provider::flag::start_transaction |
+                           wsrep::provider::flag::commit);
+    BOOST_REQUIRE(cc.enter_toi(ws_meta) == 0);
+    BOOST_REQUIRE(cc.in_toi());
+    BOOST_REQUIRE(cc.toi_mode() == wsrep::client_state::m_high_priority);
+    BOOST_REQUIRE(cc.leave_toi() == 0);
+    cc.after_applying();
+}