func TestURLPickerPickTwice(t *testing.T) {
	picker := mustNewURLPicker(t, []string{"http://127.0.0.1:2380", "http://127.0.0.1:7001"})
	u := picker.pick()
	urlmap := map[url.URL]bool{
		{Scheme: "http", Host: "127.0.0.1:2380"}: true,
		{Scheme: "http", Host: "127.0.0.1:7001"}: true,
	}
	if !urlmap[u] {
		t.Errorf("url picked = %+v, want a possible url in %+v", u, urlmap)
	}
	uu := picker.pick()
	if u != uu {
		t.Errorf("url picked = %+v, want %+v", uu, u)
	}
}
TestURLPickerPickTwice tests that pick returns a possible url,
and always returns the same one.
package rafthttp
import (
	"net/url"
	"testing"
	"github.com/coreos/etcd/pkg/testutil"
)