package netlink

import (
	"os"
	"syscall"
	"testing"
)

func init() { nlPidOnce.Do(func() {}); nlPid = 1 }

type payloadTestCase struct {
	name string
	f    func(c *conn)
	want []byte
}

// checkPayload runs multiple payloadTestCase against a stub conn and checks
// the outgoing message written to its buffer page.
func checkPayload(t *testing.T, testCases []payloadTestCase) {
	t.Helper()

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()

			c := conn{
				pos: syscall.NLMSG_HDRLEN,
				buf: make([]byte, os.Getpagesize()),
			}
			tc.f(&c)
			if got := c.pending(); string(got) != string(tc.want) {
				t.Errorf("pending: %#v, want %#v", got, tc.want)
			}
		})
	}
}