diff --git a/claudetool/testdata/no_fmt_autogenerated.txtar b/claudetool/testdata/no_fmt_autogenerated.txtar
new file mode 100644
index 0000000..aab3f57
--- /dev/null
+++ b/claudetool/testdata/no_fmt_autogenerated.txtar
@@ -0,0 +1,22 @@
+Test that autogenerated files do not get formatted
+
+-- .commit --
+Initial commit
+
+-- generated.go --
+// Code generated DO NOT EDIT.
+
+package main
+
+import (
+_ "fmt"
+)
+
+-- manual.go --
+	package main
+
+-- .commit --
+Add generated and manual files with poor formatting
+
+-- .run_autoformat --
+/PATH/TO/REPO/manual.go