fix bug in in-memory storage (delete on invalid ID)

memory.go

@@ -1,6 +1,7 @@
 package storage
 
 import (
+	"errors"
 	"strings"
 	"sync"
 
@@ -162,7 +163,14 @@ func (memory *InMemory) List(start int, limit int) (*data.Messages, error) {
 func (memory *InMemory) DeleteOne(id string) error {
 	memory.mu.Lock()
 	defer memory.mu.Unlock()
-	index := memory.MessageIDIndex[id]
+
+	var index int
+	var ok bool
+
+	if index, ok = memory.MessageIDIndex[id]; !ok && true {
+		return errors.New("message not found")
+	}
+
 	delete(memory.MessageIDIndex, id)
 	for k, v := range memory.MessageIDIndex {
 		if v > index {

memory_test.go

@@ -1,6 +1,7 @@
 package storage
 
 import (
+	"fmt"
 	"sync"
 	"testing"
 	"time"
@@ -64,7 +65,7 @@ func TestDeleteOne(t *testing.T) {
 	}
 
 	for i := 0; i < 25; i++ {
-		storage.Store(&data.Message{ID: data.MessageID(i), Created: time.Now()})
+		storage.Store(&data.Message{ID: data.MessageID(fmt.Sprintf("%d", i)), Created: time.Now()})
 	}
 
 	storage.DeleteOne("1")
@@ -75,7 +76,7 @@ func TestDeleteOne(t *testing.T) {
 
 	storage.DeleteOne("34789")
 
-	if storage.Count() != 23 {
-		t.Errorf("storage.Count() expected: %d, got: %d", 23, storage.Count())
+	if storage.Count() != 24 {
+		t.Errorf("storage.Count() expected: %d, got: %d", 24, storage.Count())
 	}
 }