package link

import (
	"testing"
)

// **Both implementations, one fixture.** The point of the seam is not that the transport can be
// swapped — it is that the two can be held to the same envelope while both ship, so the day the
// bus moves is a configuration change rather than a discovery.
//
// Against a real server, because what the fixture pins is what reaches the wire:
//
//	go test ./internal/link/ -run TestTheNatsBus   (each test on a bus of its own: internal/testbus)

// The subject a declaration lands on is one node's, and nothing else's — the state shape.
func TestADeclarationIsAddressedToOneNode(t *testing.T) {
	if got := DeclareSubject("anchor"); got != "mesh.node.anchor.declare" {
		t.Fatalf("a declaration would go to %q", got)
	}
	if DeclareSubject("anchor") == DeclareSubject("laptop") {
		t.Fatal("two nodes share a declaration subject, so each would apply the other's")
	}
}

// A module cannot emit under another's name: the subject is derived from the source, and the
// server's permissions make that subject the authority.
func TestAnEventsSubjectIsDerivedFromItsSource(t *testing.T) {
	if got := EventSubject("shop", "order.placed"); got != "mesh.mod.shop.event.order.placed" {
		t.Fatalf("an event would land on %q", got)
	}
	if EventSubject("shop", "x") == EventSubject("billing", "x") {
		t.Fatal("two modules share an event subject, so neither owns its own name")
	}
}

// A tool nobody serves says so at once. The difference between "that module is down" and "that
// tool is slow" is the first thing a person asking wants, and waiting out the timeout to say it
// is how a fast answer becomes a slow non-answer.

// And a served tool answers, with no reply queue to declare and no correlation to check.