Fix encoding test

v2/frame_test.go

@@ -4,26 +4,27 @@ import (
 	"testing"
 )
 
-func TestUnsynchTextFrame_SetEncoding(t *testing.T) {
-	f := NewUnsychTextFrame(V23CommonFrame["Comments"], "Foo", "Bar")
+func TestUnsynchTextFrameSetEncoding(t *testing.T) {
+	f := NewUnsynchTextFrame(V23CommonFrame["Comments"], "Foo", "Bar")
 	size := f.Size()
+	expectedDiff := 11
 
 	err := f.SetEncoding("UTF-16")
 	if err != nil {
 		t.Fatal(err)
 	}
 	newSize := f.Size()
-	if newSize-size != 1 {
+	if int(newSize-size) != expectedDiff {
 		t.Errorf("expected size to increase to %d, but it was %d", size+1, newSize)
 	}
 
 	size = newSize
-	err := f.SetEncoding("UTF-16")
+	err = f.SetEncoding("ISO-8859-1")
 	if err != nil {
 		t.Fatal(err)
 	}
-	newSize := f.Size()
-	if newSize-size != -1 {
+	newSize = f.Size()
+	if int(newSize-size) != -expectedDiff {
 		t.Errorf("expected size to decrease to %d, but it was %d", size-1, newSize)
 	}
 }