package inventory

import (
	"testing"
	"time"
)

// Composing and sending one node's declaration is serialised: a second holder waits for the first.
func TestHoldingANodeMakesTheNextHolderWait(t *testing.T) {
	inv := fresh(t)
	ctx := t.Context()
	release, err := inv.HoldNodes(ctx, []string{"anchor", "laptop"})
	if err != nil {
		t.Fatal(err)
	}
	got := make(chan func(), 1)
	go func() {
		second, err := inv.HoldNodes(ctx, []string{"laptop"})
		if err != nil {
			t.Error(err)
			got <- func() {}
			return
		}
		got <- second
	}()
	select {
	case <-got:
		t.Fatal("a node held by one caller was held by another at the same time")
	case <-time.After(300 * time.Millisecond):
	}
	// Another node is not held up.
	other, err := inv.HoldNodes(ctx, []string{"joiner"})
	if err != nil {
		t.Fatal(err)
	}
	other()
	release()
	select {
	case second := <-got:
		second()
	case <-time.After(5 * time.Second):
		t.Fatal("releasing the node did not let the next holder in")
	}
}