Fix deletion of non-existing keys

bucket.go

@@ -323,7 +323,12 @@ func (b *Bucket) Delete(key []byte) error {
 
 	// Move cursor to correct position.
 	c := b.Cursor()
-	_, _, flags := c.seek(key)
+	k, _, flags := c.seek(key)
+
+	// Return nil if the key doesn't exist.
+	if !bytes.Equal(key, k) {
+		return nil
+	}
 
 	// Return an error if there is already existing bucket value.
 	if (flags & bucketLeafFlag) != 0 {

bucket_test.go

@@ -425,6 +425,39 @@ func TestBucket_Delete_FreelistOverflow(t *testing.T) {
 	}
 }
 
+// Ensure that deleting of non-existing key is a no-op.
+func TestBucket_Delete_NonExisting(t *testing.T) {
+	db := MustOpenDB()
+	defer db.MustClose()
+
+	if err := db.Update(func(tx *bolt.Tx) error {
+		b, err := tx.CreateBucket([]byte("widgets"))
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if _, err = b.CreateBucket([]byte("nested")); err != nil {
+			t.Fatal(err)
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := db.Update(func(tx *bolt.Tx) error {
+		b := tx.Bucket([]byte("widgets"))
+		if err := b.Delete([]byte("foo")); err != nil {
+			t.Fatal(err)
+		}
+		if b.Bucket([]byte("nested")) == nil {
+			t.Fatal("nested bucket has been deleted")
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+}
+
 // Ensure that accessing and updating nested buckets is ok across transactions.
 func TestBucket_Nested(t *testing.T) {
 	db := MustOpenDB()