// on any ReadFrom. See golang.org/issue/35194.
func TestWriterReadFromMustReturnUnderlyingError(t *testing.T) {
	var wr = NewWriter(writeErrorOnlyWriter{})
	s := "test1"
	wantBuffered := len(s)
	if _, err := wr.WriteString(s); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if err := wr.Flush(); err == nil {
		t.Error("expected flush error, got nil")
	}