diff --git a/tests/python/test_main.py b/tests/python/test_main.py
new file mode 100644
index 0000000..df0641a
--- /dev/null
+++ b/tests/python/test_main.py
@@ -0,0 +1,24 @@
+import sys, os, json, subprocess
+
+PYTHON = sys.executable
+MAIN = os.path.join(os.path.dirname(__file__), "../../python/main.py")
+FIXTURE = os.path.join(os.path.dirname(__file__), "../fixtures/sample_template.xlsx")
+
+def _call(payload: dict) -> dict:
+    proc = subprocess.run(
+        [PYTHON, MAIN],
+        input=json.dumps(payload) + "\n",
+        capture_output=True,
+        text=True,
+        timeout=10,
+    )
+    return json.loads(proc.stdout.strip())
+
+def test_parse_template_via_stdin():
+    result = _call({"action": "parse_template", "file_path": FIXTURE})
+    assert "sheets" in result
+    assert "Sheet1" in result["sheets"]
+
+def test_unknown_action_returns_error():
+    result = _call({"action": "nonexistent"})
+    assert "error" in result