diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..6831b82
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/practo/gobatch
+
+go 1.15
diff --git a/membatch.go b/membatch.go
index ebdbd46..b022677 100644
--- a/membatch.go
+++ b/membatch.go
@@ -10,7 +10,7 @@ func NewMemoryBatch(flushMaxSize int, flushMaxWait time.Duration, callback Batch
 		maxSize: flushMaxSize,
 		maxWait: flushMaxWait,
 
-		items: make([]interface{}, flushMaxSize),
+		items: make([]interface{}, 0),
 		doFn:  callback,
 		mutex: &sync.RWMutex{},
 
@@ -30,6 +30,18 @@ func (b *Batch) Insert(data interface{}) {
 	}
 }
 
+func (b *Batch) FlushInsert(data interface{}) {
+	b.mutex.Lock()
+	defer b.mutex.Unlock()
+
+	b.Flush()
+
+	b.items = append(b.items, data)
+	if len(b.items) >= b.maxSize {
+		b.Flush()
+	}
+}
+
 func (b *Batch) runFlushByTime() {
 	for {
 		select {
diff --git a/membatch_test.go b/membatch_test.go
new file mode 100644
index 0000000..e20cf39
--- /dev/null
+++ b/membatch_test.go
@@ -0,0 +1,109 @@
+package gobatch
+
+import (
+	"fmt"
+	"testing"
+	"time"
+)
+
+type testBatchProcessor struct {
+	batchesProcessed  int
+	elementsProcessed int
+}
+
+func (b *testBatchProcessor) process(workerID int, datas []interface{}) {
+	fmt.Printf("processing: %v\n", datas)
+	b.batchesProcessed += 1
+	b.elementsProcessed += len(datas)
+	fmt.Printf("processed: %v\n\n", datas)
+}
+
+// TOOD: better way to signal back
+func waitForFlush(t int) {
+	time.Sleep(time.Duration(t) * time.Second)
+}
+
+func TestMaxSize(t *testing.T) {
+	maxSize := 5
+	maxWaitSeconds := 10
+	workers := 1
+	processor := &testBatchProcessor{}
+	mbatch := NewMemoryBatch(
+		maxSize,
+		time.Second*time.Duration(maxWaitSeconds),
+		processor.process,
+		workers,
+	)
+
+	for i := 1; i <= 3; i++ {
+		mbatch.Insert(fmt.Sprintf("element_%d", i))
+	}
+	waitForFlush(2)
+	if processor.batchesProcessed != 0 && processor.elementsProcessed != 0 {
+		t.Error("expected nothing to be processed but processing happened")
+	}
+	for i := 4; i <= 13; i++ {
+		mbatch.Insert(fmt.Sprintf("element_%d", i))
+	}
+
+	waitForFlush(2)
+	if processor.batchesProcessed != 2 && processor.elementsProcessed != 10 {
+		t.Errorf("expected 2 batch of total 10 elements, got: %+v", processor)
+	}
+	for i := 14; i <= 15; i++ {
+		mbatch.Insert(fmt.Sprintf("element_%d", i))
+	}
+
+	waitForFlush(2)
+	if processor.batchesProcessed != 3 && processor.elementsProcessed != 15 {
+		t.Errorf("expected 3 batch of total 15 elements, got: %+v", processor)
+	}
+}
+
+func TestMaxWait(t *testing.T) {
+	maxSize := 5
+	maxWaitSeconds := 7
+	workers := 1
+	processor := &testBatchProcessor{}
+	mbatch := NewMemoryBatch(
+		maxSize,
+		time.Second*time.Duration(maxWaitSeconds),
+		processor.process,
+		workers,
+	)
+
+	for i := 1; i <= 3; i++ {
+		mbatch.Insert(fmt.Sprintf("element_%d", i))
+	}
+
+	waitForFlush(9)
+	if processor.batchesProcessed != 1 && processor.elementsProcessed != 3 {
+		if processor.batchesProcessed != 1 {
+			fmt.Println(processor.batchesProcessed)
+		}
+		t.Errorf("expected 1 batch of total 3 elements, got: %+v", processor)
+	}
+}
+
+func TestFlushInsert(t *testing.T) {
+	maxSize := 5
+	maxWaitSeconds := 10
+	workers := 1
+	processor := &testBatchProcessor{}
+	mbatch := NewMemoryBatch(
+		maxSize,
+		time.Second*time.Duration(maxWaitSeconds),
+		processor.process,
+		workers,
+	)
+
+	for i := 1; i <= 3; i++ {
+		mbatch.Insert(fmt.Sprintf("element_%d", i))
+	}
+	mbatch.FlushInsert("element_4")
+
+	waitForFlush(2)
+	if processor.batchesProcessed != 1 && processor.elementsProcessed != 3 {
+		t.Errorf("expected 1 batch of total 3 elements, got: %+v", processor)
+	}
+}