Review of 083: finishing an enrolment whose token was spent takes proof of the key's private half, a live lease and a first delivery — a public key alone cannot replay a spent token; shutdown leaves held messages for the broker; identical builds supersede; what is held leaves room in the prefetch

internal/link/store_window_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"log"
 	"testing"
@@ -118,3 +119,49 @@ func TestACatchUpWaitsOutARestartingStore(t *testing.T) {
 		}
 	}
 }
+
+// Shutting down is not an answer about a message: one handled with a cancelled context is left
+// unsettled, for the broker to hand to whatever consumes next (issue 083, review).
+func TestAMessageHandledDuringShutdownIsLeftForTheBroker(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	s := quietServer()
+	s.recorder = recordsWith{err: context.Canceled}
+	to := &settledAs{}
+	s.handleBuilt(ctx, a(t, to, KeyBuilt, BuildResult{On: "anchor", Repository: "/r", Commit: "abc"}))
+	if !to.held() {
+		t.Fatalf("a build result handled during shutdown was settled, and so lost: %+v", *to)
+	}
+}
+
+// Two identical build results: the newer sets the older aside rather than leaving it unsettled
+// for ever, holding a place in the prefetch.
+func TestAnIdenticalBuildResultSetsTheHeldOneAside(t *testing.T) {
+	s := quietServer()
+	s.recorder = recordsWith{err: restarting}
+	built := BuildResult{On: "anchor", Repository: "/r", Commit: "abc"}
+	first, second := &settledAs{}, &settledAs{}
+	s.handleBuilt(context.Background(), a(t, first, KeyBuilt, built))
+	s.handleBuilt(context.Background(), a(t, second, KeyBuilt, built))
+	if !first.acked || !second.held() || len(s.parked) != 1 {
+		t.Fatalf("an identical build result did not set the held one aside: first %+v second %+v, %d held",
+			*first, *second, len(s.parked))
+	}
+}
+
+// What is held stops short of the prefetch, so the loop always has room to answer an enrolment.
+func TestWhatIsHeldLeavesRoomInThePrefetch(t *testing.T) {
+	s := quietServer()
+	s.recorder = recordsWith{err: restarting}
+	var last *settledAs
+	for i := 0; i < Prefetch; i++ {
+		last = &settledAs{}
+		s.handleBuilt(context.Background(), a(t, last, KeyBuilt, BuildResult{On: "anchor", Commit: fmt.Sprint(i)}))
+	}
+	if len(s.parked) != Prefetch-PrefetchHeadroom {
+		t.Fatalf("%d messages were held; the ceiling is %d", len(s.parked), Prefetch-PrefetchHeadroom)
+	}
+	if last.held() {
+		t.Fatalf("a message past the ceiling was held: %+v", *last)
+	}
+}