Judge a preview and a refused flip from after the performed take, which composes the node; test that a take composes only when performed (release 6, issue 1945)

cmd/mesh-controller/adopting_test.go

@@ -248,6 +248,7 @@ func TestConvergingPreviewsThenChangesAndAdoptingKeepsWhatWasTaken(t *testing.T)
 	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true}); err != nil {
 		t.Fatal(err)
 	}
+	*sent = nil // the take composed the node; what follows is judged from here
 	reportsHolding(t, open, heldFile)
 
 	preview, err := converge(ctx, open, "anchor", false, "", "")
@@ -436,6 +437,7 @@ func TestTheFlipActsOnlyOnThePreviewTheOperatorSaw(t *testing.T) {
 	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true}); err != nil {
 		t.Fatal(err)
 	}
+	*sent = nil // the take composed the node; what follows is judged from here
 	reportsHolding(t, open, heldFile)
 	preview, err := converge(ctx, open, "anchor", false, "", "")
 	if err != nil {
@@ -501,6 +503,7 @@ func TestThePreviewNamesEveryHeldKind(t *testing.T) {
 	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true}); err != nil {
 		t.Fatal(err)
 	}
+	*sent = nil // the take composed the node; what follows is judged from here
 	since := time.Now()
 	held := []link.Held{heldFile,
 		{ID: "notes.data", Module: "notes", Kind: "directory", Target: "/var/lib/notes", Since: since},
@@ -544,6 +547,7 @@ func TestTheFlipIsRefusedOnAnAccountNamingNothingReachable(t *testing.T) {
 	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true}); err != nil {
 		t.Fatal(err)
 	}
+	*sent = nil // the take composed the node; what follows is judged from here
 	// Only a loopback listener: nothing off the machine, which is the same silence.
 	reportsReaching(t, open, []link.Reach{
 		{Protocol: "tcp", Address: "127.0.0.1", Port: 15672, By: "mesh-broker"},
@@ -627,3 +631,31 @@ func TestTheFlipIsRefusedWithTheBusUnreachableSayingItCannotTell(t *testing.T) {
 		t.Fatal("a refused flip sent something")
 	}
 }
+
+// **A take composes the node only when it is performed** (issue 1945): a preview, a take that names no digest and a take refused
+// for a changed preview compose nothing; the performed take composes the machine once, and says so.
+func TestATakeComposesTheNodeOnlyWhenItIsPerformed(t *testing.T) {
+	open, sent := anAdoptedAnchor(t)
+	ctx := t.Context()
+	reportsHolding(t, open, heldContainer, heldFile)
+	preview, err := take(ctx, open, "anchor", "hello-web", takeOptions{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true}); err == nil {
+		t.Fatal("a take of a held module without the preview's digest was performed")
+	}
+	if _, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true, Digest: "not-the-digest"}); err == nil {
+		t.Fatal("a take naming another preview's digest was performed")
+	}
+	if len(*sent) != 0 {
+		t.Fatalf("a preview or a refused take composed %v", *sent)
+	}
+	said, err := take(ctx, open, "anchor", "hello-web", takeOptions{Yes: true, Digest: takeDigestIn(t, preview)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(*sent) != 1 || (*sent)[0] != "anchor" || !strings.Contains(said, "compositions of anchor are written") {
+		t.Fatalf("the performed take composed %v and said:\n%s", *sent, said)
+	}
+}