db: fix memdb iterator

db/mem_db.go

@@ -82,7 +82,7 @@ func newMemDBIterator() *memDBIterator {
 }
 
 func (it *memDBIterator) Next() bool {
-	if it.last >= len(it.keys) {
+	if it.last >= len(it.keys)-1 {
 		return false
 	}
 	it.last++

db/mem_db_test.go

@@ -0,0 +1,28 @@
+package db
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestMemDbIterator(t *testing.T) {
+	db := NewMemDB()
+	keys := make([][]byte, 100)
+	for i := 0; i < 100; i++ {
+		keys[i] = []byte{byte(i)}
+	}
+
+	value := []byte{5}
+	for _, k := range keys {
+		db.Set(k, value)
+	}
+
+	iter := db.Iterator()
+	i := 0
+	for iter.Next() {
+		assert.Equal(t, db.Get(iter.Key()), iter.Value(), "values dont match for key")
+		i += 1
+	}
+	assert.Equal(t, i, len(db.db), "iterator didnt cover whole db")
+}