package store

import (
	"path/filepath"
	"testing"
	"time"
)

// Defends the node's record across processes: a `reconcile` run by hand beside the link service,
// or the installer beside either, waits for the other's apply rather than saving over it.
func TestASecondApplyWaitsForTheFirst(t *testing.T) {
	state := filepath.Join(t.TempDir(), "state.json")
	release, err := Lock(state, nil)
	if err != nil {
		t.Fatal(err)
	}

	waited := make(chan struct{}, 1)
	got := make(chan struct{})
	go func() {
		unlock, err := Lock(state, func() { waited <- struct{}{} })
		if err != nil {
			t.Error(err)
		}
		close(got)
		unlock()
	}()

	select {
	case <-waited:
	case <-time.After(5 * time.Second):
		t.Fatal("the second apply was not told it is waiting")
	}
	select {
	case <-got:
		t.Fatal("the second apply took the lock while the first held it")
	case <-time.After(50 * time.Millisecond):
	}
	release()
	select {
	case <-got:
	case <-time.After(5 * time.Second):
		t.Fatal("the second apply never got the lock once the first let go")
	}
}