OpenPGP signatures: added test dir with example.

tests/test_sign.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""Test how to OpenPGP sign data for emails.
+
+First revision without test framework to be directly run.
+
+Dependencies:
+ * pygpgme build for python3
+Authors:
+ *  Bernhard E. Reiter <bernhard@intevation.de>
+"""
+
+import gpgme
+from io import BytesIO
+
+def test_sign_nomime():
+    #TODO setup a separate GNUPGHOME
+    email_body = """Hello,
+
+    this is my email body,
+    which shall be signed."""
+
+    ctx = gpgme.Context()
+
+    #TODO create or find test-key
+    key = ctx.get_key('2E17923D761D9154B2C1A1763C43F4C8EFF5D42A')
+    ctx.signers = [key]
+
+    #plaintext = BytesIO(b"Hello World!")
+    plaintext = BytesIO(email_body.encode())
+    signature = BytesIO()
+    sig = ctx.sign(plaintext, signature, gpgme.SIG_MODE_CLEAR)
+
+    signature.seek(0)
+    print(signature.read().decode(), sig[0])
+
+if __name__ == "__main__":
+    test_sign_nomime()