Prove a later assignments-stream membership changes nothing once the grants part's state has given one (issue 1955, ADR 0571 clause 7)

node-tools/internal/bus/streams_test.go

@@ -182,7 +182,6 @@ func TestAModuleHearsEveryStreamItsMembershipNames(t *testing.T) {
 	if got := consumerOf(); got != "from-grants" {
 		t.Fatalf("the membership read at the follow names %q, want the grants part's", got)
 	}
-	mesh.Issue(t, reader)
 	granted.Hears[0].Consumer = "from-grants-2"
 	mesh.IssueInGrants(t, granted)
 	mt.Until(t, func() error {
@@ -191,6 +190,39 @@ func TestAModuleHearsEveryStreamItsMembershipNames(t *testing.T) {
 		}
 		return nil
 	})
+	// A later, different copy on the assignments stream changes nothing once the state has given one.
+	arrived := make(chan struct{}, 1)
+	probe, err := bus.Connect(bus.Credential{URL: mt.URL(t), Module: "probe", Node: "elsewhere"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	probe.Logf = func(string, ...any) {}
+	t.Cleanup(probe.Close)
+	stopProbe, err := probe.Raw(bus.MembershipSubject("anchor", "reader"), func(string, []byte) []byte {
+		select {
+		case arrived <- struct{}{}:
+		default:
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(stopProbe)
+	probe.Flush()
+	streamed := reader
+	streamed.Hears = []bus.HeardIssued{{Stream: "MAIL", Consumer: "from-stream"}}
+	mesh.Issue(t, streamed)
+	select {
+	case <-arrived:
+	case <-time.After(5 * time.Second):
+		t.Fatal("the stream's copy was not published")
+	}
+	again.Flush()
+	time.Sleep(200 * time.Millisecond)
+	if got := consumerOf(); got != "from-grants-2" {
+		t.Fatalf("the stream's copy was applied over the grants part's: the membership names %q", got)
+	}
 }
 
 // novox/hq ADR 0363 §6 (issue 725): a consumer the membership names before the controller made it is bound once