From 100b248fc99ed759de1fb5b74dafea43929b76e9 Mon Sep 17 00:00:00 2001
From: jules01 <iulian.pascalau@gmail.com>
Date: Mon, 18 Sep 2023 21:56:15 +0300
Subject: [PATCH] - added unit test

---
 leveldb/export_test.go        |  6 ++++
 leveldb/leveldbSerial_test.go | 58 +++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)
 create mode 100644 leveldb/export_test.go

diff --git a/leveldb/export_test.go b/leveldb/export_test.go
new file mode 100644
index 00000000..dcd88bf4
--- /dev/null
+++ b/leveldb/export_test.go
@@ -0,0 +1,6 @@
+package leveldb
+
+// PutBatch will call the unexported putBatch function
+func (s *SerialDB) PutBatch() {
+	_ = s.putBatch()
+}
diff --git a/leveldb/leveldbSerial_test.go b/leveldb/leveldbSerial_test.go
index f8b39827..7716e2b6 100644
--- a/leveldb/leveldbSerial_test.go
+++ b/leveldb/leveldbSerial_test.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math/big"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -358,3 +359,60 @@ func TestSerialDB_ConcurrentOperations(t *testing.T) {
 
 	wg.Wait()
 }
+
+func TestSerialDB_PutRemoveGet(t *testing.T) {
+	if testing.Short() {
+		t.Skip("this is not a short test")
+	}
+
+	ldb := createSerialLevelDb(t, 100000, 1000000, 10)
+
+	numKeys := 10000
+	for i := 0; i < numKeys; i++ {
+		_ = ldb.Put([]byte(fmt.Sprintf("key %d", i)), []byte("val"))
+	}
+
+	time.Sleep(time.Second * 2)
+
+	numErr := uint32(0)
+
+	for i := 0; i < numKeys; i++ {
+		key := []byte(fmt.Sprintf("key %d", i))
+
+		recoveredVal, _ := ldb.Get(key)
+		assert.NotEmpty(t, recoveredVal)
+
+		wg := &sync.WaitGroup{}
+		wg.Add(2)
+
+		// emulate the following scenario:
+		// the sequence Remove(key) -> Get(key) is done while the putBatch is called. So the actual edgecase is
+		// go routine 1: Remove(key) -----------------> Get(key)
+		// go routine 2:                putBatch()
+
+		go func() {
+			time.Sleep(time.Millisecond * 1)
+			ldb.PutBatch()
+			wg.Done()
+		}()
+		go func() {
+			_ = ldb.Remove(key)
+
+			time.Sleep(time.Millisecond * 1)
+
+			recoveredVal2, _ := ldb.Get(key)
+			if len(recoveredVal2) > 0 {
+				// the key-value was not removed
+				atomic.AddUint32(&numErr, 1)
+			}
+
+			wg.Done()
+		}()
+
+		wg.Wait()
+
+		require.Zero(t, atomic.LoadUint32(&numErr), "iteration %d out of %d", i, numKeys)
+	}
+
+	_ = ldb.Close()
+}