if err := res.Body.Close(); err != nil {
		t.Errorf("Close = %v", err)
	}

	if err := <-writeErr; err == nil {
		t.Errorf("expected non-nil write error")
	}
}

type fooProto struct{}

func (fooProto) RoundTrip(req *Request) (*Response, error) {
	res := &Response{
		Status:     "200 OK",
		StatusCode: 200,
		Header:     make(Header),