b := NewReader(new(negativeReader))
	defer func() {
		switch err := recover().(type) {
		case nil:
			t.Fatal("read did not panic")
		case error:
			if !strings.Contains(err.Error(), "reader returned negative count from Read") {
				t.Fatalf("wrong panic: %v", err)
			}
		default:
			t.Fatalf("unexpected panic value: %T(%v)", err, err)
		}
	}()