// leaked goroutines.
	if got, want := res.Header.Get("Foo"), "Bar"; got != want {
		t.Errorf("Foo header = %q; want %q", got, want)
	}
}

type closerFunc func() error

func (f closerFunc) Close() error { return f() }

type writerFuncConn struct {
	net.Conn
	write func(p []byte) (n int, err error)
}

type rwTestConn struct {
	io.Reader
	io.Writer
	noopConn

	closeFunc func() error // called if non-nil
	closec    chan bool    // else, if non-nil, send value to it on close
}

func (c *rwTestConn) Close() error {
	if c.closeFunc != nil {
		return c.closeFunc()
	}
	select {
	case c.closec <- true:
	default:
	}
	return nil
}

type testConn struct {