diff --git a/fud2/tests/snapshots/tests__list_ops.snap b/fud2/tests/snapshots/tests__list_ops.snap
index ed1652224..8f9003535 100644
--- a/fud2/tests/snapshots/tests__list_ops.snap
+++ b/fud2/tests/snapshots/tests__list_ops.snap
@@ -1,5 +1,6 @@
 ---
 source: fud2/tests/tests.rs
+assertion_line: 251
 ---
 [
     (
@@ -37,6 +38,11 @@ source: fud2/tests/tests.rs
         "calyx",
         "yxi",
     ),
+    (
+        "calyx_py-to-calyx",
+        "calyx_py",
+        "calyx",
+    ),
     (
         "cider",
         "cider",
diff --git a/fud2/tests/snapshots/tests__list_states.snap b/fud2/tests/snapshots/tests__list_states.snap
index 8872d6c33..de09a7c58 100644
--- a/fud2/tests/snapshots/tests__list_states.snap
+++ b/fud2/tests/snapshots/tests__list_states.snap
@@ -1,8 +1,10 @@
 ---
 source: fud2/tests/tests.rs
+assertion_line: 229
 ---
 [
     "calyx",
+    "calyx_py",
     "cider",
     "cider-debug",
     "cocotb-axi",
diff --git a/fud2/tests/snapshots/tests__test@plan_calyx_py-to-calyx.snap b/fud2/tests/snapshots/tests__test@plan_calyx_py-to-calyx.snap
new file mode 100644
index 000000000..a2879431e
--- /dev/null
+++ b/fud2/tests/snapshots/tests__test@plan_calyx_py-to-calyx.snap
@@ -0,0 +1,16 @@
+---
+source: fud2/tests/tests.rs
+assertion_line: 66
+description: "emit plan: calyx_py-to-calyx"
+---
+build-tool = fud2
+rule get-rsrc
+  command = $build-tool get-rsrc $out
+
+py_args = 
+rule calyx_py-to-calyx
+  command = python3 $in $py_args > $out
+
+build /output.ext: calyx_py-to-calyx /input.ext
+
+default /output.ext