1 files changed, 80 insertions, 0 deletions
diff --git a/internal/engine/undo_identity_test.go b/internal/engine/undo_identity_test.go
index f9d6307..f42c5da 100644
--- a/internal/engine/undo_identity_test.go
+++ b/internal/engine/undo_identity_test.go
@@ -492,3 +492,83 @@ func TestUndoRefusesATrashEntryRecordedForAnotherPath(t *testing.T) {
 		t.Errorf("Refused = %q; want the trash entry named as another file's", f.Refused)
 	}
 }
+
+// TestFinishedUndoRemovesADirectoryLeftEmpty: a directory made by one file's
+// chain and still holding another file is not offered on its own, but once
+// that other file's reversal empties it, the undo removes it (plan 10
+// re-check R1).
+func TestFinishedUndoRemovesADirectoryLeftEmpty(t *testing.T) {
+	e, run, h, logPath := appliedRun(t, map[string]map[string]string{"dl": {"a.pdf": "one", "b.pdf": "two"}},
+		map[string]string{"dl": "(path \"~/dl\")\n(rule \"r\" (move \"Out\"))\n"})
+	out := filepath.Join(h, "dl", "Out")
+	undo := func(decline string) {
+		t.Helper()
+		up, err := e.PlanUndo(run)
+		if err != nil {
+			t.Fatal(err)
+		}
+		for i := range up.Files {
+			up.Files[i].Declined = up.Files[i].File == decline
+		}
+		j, err := journal.Open(logPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer j.Close()
+		if _, err := e.ApplyUndo(context.Background(), up, j, journal.NewRunID(time.Now())); err != nil {
+			t.Fatal(err)
+		}
+	}
+	up, err := e.PlanUndo(run)
+	if err != nil {
+		t.Fatal(err)
+	}
+	other := ""
+	for _, f := range up.Files {
+		made := false
+		for _, s := range f.Steps {
+			made = made || s.Action == "undo-mkdir"
+		}
+		if !made {
+			other = f.File
+		}
+	}
+	undo(other) // the file that made Out goes back; the other still holds Out
+	if _, err := os.Stat(out); err != nil {
+		t.Fatalf("Out went while %s still held it: %v", other, err)
+	}
+	undo("") // the other goes back, leaving Out empty
+	if _, err := os.Lstat(out); !os.IsNotExist(err) {
+		t.Errorf("Out is still there after the undo finished: %v", err)
+	}
+}
+
+// TestUndoRunWithADamagedLineIsStillAnUndo: a damaged line in an undo run's
+// log does not make that run look like an ordinary one that can be undone
+// (plan 10 re-check R3).
+func TestUndoRunWithADamagedLineIsStillAnUndo(t *testing.T) {
+	e, run, _, logPath := appliedRun(t, map[string]map[string]string{"dl": {"a.pdf": "one"}},
+		map[string]string{"dl": "(path \"~/dl\")\n(rule \"r\" (rename \"r-{name}\") (move \"Out\"))\n"})
+	up, err := e.PlanUndo(run)
+	if err != nil {
+		t.Fatal(err)
+	}
+	j, err := journal.Open(logPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	undoRun := journal.NewRunID(time.Now().Add(time.Second))
+	if _, err := e.ApplyUndo(context.Background(), up, j, undoRun); err != nil {
+		t.Fatal(err)
+	}
+	j.Close()
+	f, err := os.OpenFile(logPath, os.O_APPEND|os.O_WRONLY, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.WriteString(time.Now().UTC().Format(time.RFC3339) + "\t" + undoRun + "\tdl\ta.pdf\t9\tundo-mo\n")
+	f.Close()
+	if _, err := e.PlanUndo(undoRun); err == nil || !strings.Contains(err.Error(), "itself an undo") {
+		t.Errorf("PlanUndo(undo run with a damaged line) = %v; want refused as an undo", err)
+	}
+}