diff --git a/tests/wave8_signature_envelope_test.py b/tests/wave8_signature_envelope_test.py
new file mode 100644
index 00000000..329ed676
--- /dev/null
+++ b/tests/wave8_signature_envelope_test.py
@@ -0,0 +1,15 @@
+import unittest
+
+class TestWave8SignatureEnvelope(unittest.TestCase):
+    def test_signature_payload_non_empty(self):
+        def is_valid_envelope(signature: str, public_key: str) -> bool:
+            return bool(signature and public_key and len(public_key) == 56)
+
+        valid_pk = "GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5"
+        dummy_sig = "a" * 128
+        self.assertTrue(is_valid_envelope(dummy_sig, valid_pk))
+        self.assertFalse(is_valid_envelope("", valid_pk))
+        self.assertFalse(is_valid_envelope(dummy_sig, "short_key"))
+
+if __name__ == '__main__':
+    unittest.main()