Seat list reader: an integration case over a real bus, from the bootstrap alone to the seat's answer and its events (ADR 0636 §8; issue 1966)

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig
2026-11-05 13:45:30 +01:00
parent 351f8abba7
commit b7ad47ab2a
1 changed files with 107 additions and 0 deletions
@@ -0,0 +1,107 @@
+//go:build integration
+
+package seatlist_test
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/seatdef"
+	"git.novox.be/novox/mesh-sdk/go/seatlist"
+	"git.novox.be/novox/mesh-sdk/go/testbus"
+)
+
+// natsBus is a reader's bus over a real NATS connection: a seat verb is a request on the seat's tool subject, a seat's
+// event a subscription on its event subject.
+type natsBus struct{ c *nats.Conn }
+
+func (b natsBus) Ask(key string, body any) (json.RawMessage, error) {
+	seat, verb, _ := strings.Cut(strings.TrimPrefix(key, "seat:"), ".")
+	raw, _ := json.Marshal(body)
+	m, err := b.c.Request("mesh.seat."+seat+".tool."+verb, raw, time.Second)
+	if err != nil {
+		return nil, err
+	}
+	return m.Data, nil
+}
+
+func (b natsBus) Subscribe(pattern string, handle func(string, json.RawMessage) error) error {
+	seat, event, _ := strings.Cut(pattern, ".")
+	_, err := b.c.Subscribe(seatdef.EventSubject(seat, event), func(m *nats.Msg) {
+		_ = handle(seat+"."+event, m.Data)
+	})
+	return err
+}
+
+// ADR 0636 §8: a reader started with only the bootstrapped definitions, and the seat not yet serving, acts on the bootstrapped
+// modules alone and holds nothing new; when the seat answers it reads the whole list, and it follows the seat's changed and
+// removed events, over a real bus.
+func TestAReaderStartsFromTheBootstrapAndReadsTheSeatOnceItAnswers(t *testing.T) {
+	c, err := nats.Connect(testbus.URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+	bus := natsBus{c}
+	changed := make(chan string, 8)
+	r, err := seatlist.Start(seatlist.Config{Bus: bus, Bootstrap: seatlist.Bootstrapped(),
+		OnChange: func([]catalogue.Seat) { changed <- "changed" }})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if st := r.Status(); st.Heard || st.LastError == "" || !r.MayAct("node-engine") || r.MayAct("node-files") {
+		t.Fatalf("with the seat silent: %+v, may act on node-files: %v", st, r.MayAct("node-files"))
+	}
+
+	table := map[string]string{"node-files": `{"format":1,"seat":"node-files","scope":"node","grain":"seat-list","decision":"ADR 1",` +
+		`"verbs":[{"name":"read","input":{"type":"object"}}]}`}
+	serve := func(m *nats.Msg) {
+		var q struct {
+			Seat string `json:"seat"`
+		}
+		_ = json.Unmarshal(m.Data, &q)
+		if q.Seat == "" {
+			out, _ := json.Marshal(seatlist.Listing{Revision: 3, Seats: []seatlist.Entry{{Seat: "node-files", Source: seatlist.SourceTrunk, Digest: "d1"}}})
+			_ = m.Respond(out)
+			return
+		}
+		out, _ := json.Marshal(seatlist.Answer{Seat: q.Seat, Found: true, Revision: 3,
+			Entry: &seatlist.Entry{Seat: q.Seat, Source: seatlist.SourceTrunk, Digest: "d1", Definition: json.RawMessage(table[q.Seat])}})
+		_ = m.Respond(out)
+	}
+	if _, err := c.Subscribe("mesh.seat."+seatlist.Seat+".tool."+seatlist.Verb, serve); err != nil {
+		t.Fatal(err)
+	}
+	// The seat says a definition changed: the silent reader reads the list at the event, not on a timer.
+	if err := c.Publish(seatdef.EventSubject(seatlist.Seat, seatlist.ChangedEvent), []byte(`{"seat":"node-files","source":"trunk","digest":"d1"}`)); err != nil {
+		t.Fatal(err)
+	}
+	until(t, changed, func() bool { return r.Has("node-files") })
+	if err := r.Reload(); err != nil {
+		t.Fatal(err)
+	}
+	if st := r.Status(); !st.Heard || st.LastError != "" || !r.MayAct("node-files") || st.Revision != 3 {
+		t.Fatalf("after the seat answered: %+v", st)
+	}
+	if err := c.Publish(seatdef.EventSubject(seatlist.Seat, seatlist.RemovedEvent), []byte(`{"seat":"node-files"}`)); err != nil {
+		t.Fatal(err)
+	}
+	until(t, changed, func() bool { return !r.Has("node-files") })
+}
+
+// until waits for the reader's own notice of a change (OnChange), never a sleep, until ok holds.
+func until(t *testing.T, changed <-chan string, ok func() bool) {
+	t.Helper()
+	for !ok() {
+		select {
+		case <-changed:
+		case <-time.After(5 * time.Second):
+			t.Fatal("the reader did not follow the seat's event")
+		}
+	}
+}