if buf.String() != want {
		t.Errorf("enc.EncodeToken: expected %q; got %q", want, buf.String())
	}
}

// Issue 16158. Decoder.unmarshalAttr ignores the return value of copyValue.
func TestIssue16158(t *testing.T) {
	const data = `<foo b="HELLOWORLD"></foo>`
	err := Unmarshal([]byte(data), &struct {
		B byte `xml:"b,attr,omitempty"`
	}{})
	if err == nil {