Give a work-queue stream its one consumer, drop-only dead letters (issue 1178)

internal/link/deadletters_work_queue_test.go

@@ -0,0 +1,50 @@
+package link
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/nats-io/nats.go"
+)
+
+// A work-queue stream's dead letters are kept and shown as a restricted stream's are — aged with the
+// stream, never with their body or headers — and can only be dropped, never delivered again (novox/hq ADR
+// 0436 §6, changing ADR 0363 §7 for such a stream).
+
+// 1178/AC3: a dead letter's headers say it came from a work-queue stream, and reading it back carries that
+// (and the restricted flag its aging and hiding already key off, deadLetterOf being the one place both are
+// read: see DeadLetter.Restricted's doc).
+func TestAWorkQueueDeadLettersHeaderIsReadBack(t *testing.T) {
+	agesOut := time.Now().Add(time.Hour).UTC()
+	h := nats.Header{}
+	h.Set(DeadHeaderStream, "MAIL_SENDS")
+	h.Set(DeadHeaderConsumer, "novox_mesh-mail_send")
+	h.Set(DeadHeaderSubject, "mesh.stream.mesh-mail.event.mail.send.approved")
+	h.Set(DeadHeaderRestricted, "true")
+	h.Set(DeadHeaderWorkQueue, "true")
+	h.Set(DeadHeaderAgesOut, agesOut.Format(time.RFC3339Nano))
+
+	d := deadLetterOf(42, "mesh.stream.mesh-mail.event.mail.send.approved", h, []byte("secret body"), false)
+	if !d.WorkQueue {
+		t.Fatalf("a work-queue dead letter read as %+v", d)
+	}
+	if !d.Restricted {
+		t.Fatalf("a work-queue dead letter is not read as restricted, so it would be shown with its body: %+v", d)
+	}
+	if !d.AgesOut.Equal(agesOut) {
+		t.Fatalf("ages out at %v, want %v — it should age with its stream", d.AgesOut, agesOut)
+	}
+}
+
+// 1178/AC3: asking to deliver a work-queue dead letter again is refused, naming ADR 0436 clause 6 — before
+// anything is asked of the bus, so it holds whatever max-deliver or age is left.
+func TestAWorkQueueDeadLetterIsNeverDeliveredAgain(t *testing.T) {
+	d := DeadLetter{ID: 7, Stream: "MAIL_SENDS", Consumer: "novox_mesh-mail_send",
+		Subject: "mesh.stream.mesh-mail.event.mail.send.approved", WorkQueue: true, Restricted: true,
+		AgesOut: time.Now().Add(time.Hour)}
+	if _, err := AgainTo(nil, d); err == nil || !strings.Contains(err.Error(), "ADR 0436 clause 6") ||
+		!strings.Contains(err.Error(), "Drop it") {
+		t.Fatalf("delivering a work-queue dead letter again: %v; want a refusal naming ADR 0436 clause 6", err)
+	}
+}