Leave a module out of a send when the store lacks its image, and say it (issue 1742)

internal/builder/registry_test.go

@@ -252,3 +252,32 @@ func TestAPushedImageComesBackPinned(t *testing.T) {
 		t.Fatalf("it did not tag and then push: %v", ran)
 	}
 }
+
+// 1742: an image pushed under other names before lists their digests too, and the digest recorded is the one of the name
+// this push made — never the first listed, which may be another repository's.
+func TestThePinnedDigestIsTheOneOfTheNamePushed(t *testing.T) {
+	want := "registry.invalid/shell/server@sha256:" + strings.Repeat("b", 64)
+	earlier := "registry.invalid/scratch/shell/server@sha256:" + strings.Repeat("a", 64)
+	r := Registry{Address: "registry.invalid", Run: func(
+		_ context.Context, _, name string, args ...string) (string, error) {
+		if name == "docker" && len(args) > 0 && args[0] == "inspect" {
+			return earlier + "\n" + want + "\n", nil
+		}
+		return "", nil
+	}}
+	got, err := r.PublishImage(context.Background(), "local", "shell/server")
+	if err != nil || got != want {
+		t.Fatalf("pinned %q (%v); want %q", got, err, want)
+	}
+	// Only another repository's digest is listed: the push is not taken for pinned.
+	r.Run = func(_ context.Context, _, name string, args ...string) (string, error) {
+		if name == "docker" && len(args) > 0 && args[0] == "inspect" {
+			return earlier + "\n", nil
+		}
+		return "", nil
+	}
+	if _, err := r.PublishImage(context.Background(), "local", "shell/server"); err == nil ||
+		!strings.Contains(err.Error(), "no digest for that name") {
+		t.Fatalf("a digest of another repository was taken for the push's own: %v", err)
+	}
+}