diff --git a/shirakami/test/ApiTest.cpp b/shirakami/test/ApiTest.cpp
index 0245da6..76cdad2 100644
--- a/shirakami/test/ApiTest.cpp
+++ b/shirakami/test/ApiTest.cpp
@@ -1442,6 +1442,10 @@ TEST_F(ShirakamiApiTest, tracking) {
 }
 
 TEST_F(ShirakamiApiTest, transaction_begin_and_commit) {
+    // verify two conflicting transactions repeat begin/commit and finally meet the goal
+    // note: even if this test fails intermittently, you don't need to worry if re-run is successful
+    // due to the environment or resource, the test may fail in low probability
+    constexpr std::size_t retry = 200;
     DatabaseOptions options;
     options.attribute(KEY_LOCATION, path());
     DatabaseHandle db;
@@ -1500,7 +1504,7 @@ TEST_F(ShirakamiApiTest, transaction_begin_and_commit) {
     ASSERT_EQ(transaction_exec(db, {}, &S::prepare, &s), StatusCode::OK);
     auto r1 = std::async(std::launch::async, [&] {
         std::size_t count = 5;
-        for (std::size_t i = 0U; i < 100U; ++i) {
+        for (std::size_t i = 0U; i < retry; ++i) {
             if (S::run(db, s)) {
                 count--;
                 if (count == 0) {
@@ -1513,7 +1517,7 @@ TEST_F(ShirakamiApiTest, transaction_begin_and_commit) {
     });
     std::size_t count = 5;
     bool success = false;
-    for (std::size_t i = 0U; i < 100U; ++i) {
+    for (std::size_t i = 0U; i < retry; ++i) {
         if (S::run(db, s)) {
             count--;
             if (count == 0) {
diff --git a/shirakami/test/ccTest.cpp b/shirakami/test/ccTest.cpp
index de776b4..6b694fc 100644
--- a/shirakami/test/ccTest.cpp
+++ b/shirakami/test/ccTest.cpp
@@ -290,8 +290,26 @@ TEST_F(ShirakamiCCTest, scan_and_delete) {
         EXPECT_EQ(tx3->commit(), StatusCode::OK);
         return true;
     });
-    EXPECT_GE(r1.get(), 2);
     EXPECT_TRUE(r2.get());
+    {
+        std::unique_ptr<Transaction> tx{};
+        EXPECT_EQ(StatusCode::OK, db->create_transaction(tx));
+        std::unique_ptr<Storage> st{};
+        EXPECT_EQ(db->get_storage("S", st), StatusCode::OK);
+        std::unique_ptr<Iterator> it{};
+        EXPECT_EQ(st->scan(tx.get(),
+                "", EndPointKind::UNBOUND,
+                "", EndPointKind::UNBOUND,
+                it), StatusCode::OK);
+        auto iter = test_iterator(std::move(it));
+        StatusCode rc{};
+        std::size_t row_count = 0;
+        while((rc = iter->next()) == StatusCode::OK) {
+            ++row_count;
+        }
+        EXPECT_EQ(tx->commit(), StatusCode::OK);
+        EXPECT_EQ(row_count, 0);
+    }
     EXPECT_EQ(db->close(), StatusCode::OK);
 }