1 files changed, 18 insertions, 0 deletions
diff --git a/internal/engine/roundtrip_test.go b/internal/engine/roundtrip_test.go
index 425dc1a..67de507 100644
--- a/internal/engine/roundtrip_test.go
+++ b/internal/engine/roundtrip_test.go
@@ -159,3 +159,21 @@ func TestApplyThenUndoRestoresTheTree(t *testing.T) {
 		t.Errorf("reading backup dir after undo: %v", err)
 	}
 }
+
+// TestUndoReversesChainsWithinOneFile is the property test's first finding
+// (plan 8, Task 9): undo judged each move and rename against the disk as it
+// is now, so the first step of a chain - a rename then a move, two moves, a
+// move then trash - found its destination empty, because the later step had
+// already moved the file on, and the whole file was refused.
+func TestUndoReversesChainsWithinOneFile(t *testing.T) {
+	for name, rule := range map[string]string{
+		"rename then move": `(rule "r" (rename "r-{name}") (move "Out"))`,
+		"move then move":   `(rule "r" (move "Out") (move "Out/{mtime:%Y}"))`,
+		"move then trash":  `(rule "r" (move "Out") (delete))`,
+		"rename twice":     `(rule "r" (rename "r-{name}") (rename "r-{name}"))`,
+	} {
+		t.Run(name, func(t *testing.T) {
+			checkApplyUndo(t, propertyCase{files: map[string]string{"a.pdf": "one"}, rules: "(path \"~/dl\")\n" + rule + "\n"})
+		})
+	}
+}