pytest: Add test for keysend extra-tlvs

tests/plugins/sphinx-receiver.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+from pyln.client import Plugin
+
+
+plugin = Plugin()
+
+
+@plugin.hook('invoice_payment')
+def on_invoice_payment(**kwargs):
+    """
+    """
+    plugin.log("invoice_payment kwargs {a}".format(a=kwargs))
+    return {'result': 'continue'}
+
+
+plugin.run()