storage: add seek implementation

during testing found missing Seek() implementation for inmemorydb

pkg/core/storage/memory_store.go

@@ -2,6 +2,7 @@ package storage
 
 import (
 	"encoding/hex"
+	"strings"
 	"sync"
 )
 
@@ -67,6 +68,12 @@ func (s *MemoryStore) PutBatch(batch Batch) error {
 
 // Seek implements the Store interface.
 func (s *MemoryStore) Seek(key []byte, f func(k, v []byte)) {
+	for k, v := range s.mem {
+		if strings.Contains(k, hex.EncodeToString(key)) {
+			decodeString, _ := hex.DecodeString(k)
+			f(decodeString, v)
+		}
+	}
 }
 
 // Batch implements the Batch interface and returns a compatible Batch.

pkg/core/storage/memory_store_test.go

@@ -59,3 +59,19 @@ func TestPutBatch(t *testing.T) {
 	assert.Equal(t, value, newVal)
 	require.NoError(t, s.Close())
 }
+
+func TestMemoryStore_Seek(t *testing.T) {
+	var (
+		s     = NewMemoryStore()
+		key   = []byte("sparse")
+		value = []byte("rocks")
+	)
+
+	if err := s.Put(key, value); err != nil {
+		t.Fatal(err)
+	}
+
+	s.Seek(key, func(k, v []byte) {
+		assert.Equal(t, value, v)
+	})
+}