Keep what an adopted node reports holding, the firewall it found and what is reachable on it (hq ADR 0100)

internal/link/heard_test.go

@@ -175,3 +175,46 @@ func TestAFailureDoesNotBecomeTheAccountOfWhatTheMachineHolds(t *testing.T) {
 		t.Fatalf("a partial report replaced the account of what the machine holds: %v", owned)
 	}
 }
+
+// novox/hq ADR 0100: what an adopted node holds, the firewall it found and what is reachable on it
+// are kept from the report that carries them, and a bare word that the node is there wipes none.
+func TestWhatAnAdoptedNodeHoldsIsKeptAndAnAliveWordDoesNotWipeIt(t *testing.T) {
+	inv, _, _ := heardFrom(t, link.Report{
+		Node: "anchor", Applied: []string{"hello-web.served"}, Firewall: "ufw",
+		Held: []link.Held{{ID: "hello-web.page", Module: "hello-web", Kind: "file",
+			Target: "/var/lib/hello-web/index.html", Changed: "rewritten", Kept: "/var/lib/mesh/kept/x"}},
+		Reachable: []link.Reach{{Protocol: "tcp", Address: "0.0.0.0", Port: 8080, By: "hello-web",
+			Published: true, ContainerPort: 80}},
+	})
+	ctx := context.Background()
+	check := func(when string) {
+		t.Helper()
+		got, err := inv.AdoptionOf(ctx, "anchor")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if got.Firewall != "ufw" || len(got.Held) != 1 || got.Held[0].Changed != "rewritten" ||
+			len(got.Reachable) != 1 || got.Reachable[0].ContainerPort != 80 || got.At.IsZero() {
+			t.Fatalf("%s: what the node said is not what was kept: %+v", when, got)
+		}
+	}
+	check("after the report")
+
+	if err := (link.Enrolment{Inventory: inv}).Heard(ctx, link.Report{Node: "anchor"}); err != nil {
+		t.Fatal(err)
+	}
+	check("after an alive word")
+
+	// A reconcile report carrying only adoption is recorded, though it applied nothing.
+	if err := (link.Enrolment{Inventory: inv}).Heard(ctx, link.Report{Node: "anchor",
+		Firewall: "ufw"}); err != nil {
+		t.Fatal(err)
+	}
+	got, err := inv.AdoptionOf(ctx, "anchor")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got.Held) != 0 || got.Firewall != "ufw" {
+		t.Fatalf("a report from an adopted node holding nothing did not empty held: %+v", got)
+	}
+}