diff --git a/claudetool/codereview/testdata/generate_success.txtar b/claudetool/codereview/testdata/generate_success.txtar
new file mode 100644
index 0000000..b6b6183
--- /dev/null
+++ b/claudetool/codereview/testdata/generate_success.txtar
@@ -0,0 +1,49 @@
+Test go generate as part of mechanical checks
+
+-- go.mod --
+module sketch.dev
+
+go 1.23
+
+-- .commit --
+Initial commit
+
+-- gen.go --
+//go:build ignore
+
+package main
+
+import (
+	"os"
+)
+
+func main() {
+	f, _ := os.Create("generated.go")
+	defer f.Close()
+	f.WriteString("// Code generated by go generate; DO NOT EDIT.\n")
+	f.WriteString("package main\n")
+	f.WriteString("const GeneratedValue = 42\n")
+}
+
+-- main.go --
+package main
+
+//go:generate go run gen.go
+
+func main() {
+	println("Hello, world!")
+}
+
+-- .commit --
+Initial commit with go generate directive
+
+-- .run_test --
+# Info
+
+The following files were changed by running `go generate`:
+
+/PATH/TO/REPO/generated.go
+
+Please amend your latest git commit with these changes.
+
+