Add another msg id extractor test

2 files changed, 32 insertions, 2 deletions

diff --git a/distixlib/msg_id_extractor.py b/distixlib/msg_id_extractor.py
index cbe985d..d789e90 100644
--- a/distixlib/msg_id_extractor.py
+++ b/distixlib/msg_id_extractor.py
@@ -16,6 +16,22 @@
 # =*= License: GPL-3+ =*=
 
 
+import email
+
 
 def get_ids_from_message(msg):
-    return []
+    return set(_yield_ids(msg))
+
+
+def _yield_ids(msg):
+    header_names = ('Message-Id', 'In-Reply-To', 'References')
+    for header_name in header_names:
+        for msg_id in _yield_ids_from_header(msg, header_name):
+            yield msg_id
+
+
+def _yield_ids_from_header(msg, header_name):
+    values = msg.get_all(header_name)
+    if values:
+        for _, msg_id in email.utils.getaddresses(values):
+            yield msg_id
diff --git a/distixlib/msg_id_extractor_tests.py b/distixlib/msg_id_extractor_tests.py
index 6a7e259..b47b0f3 100644
--- a/distixlib/msg_id_extractor_tests.py
+++ b/distixlib/msg_id_extractor_tests.py
@@ -33,4 +33,18 @@ Subject: O, Romeo
 Wherefore art thou?
 ''')
 
-        self.assertEqual(distixlib.get_ids_from_message(msg), [])
+        self.assertEqual(distixlib.get_ids_from_message(msg), set())
+
+    def test_returns_id_from_message_id(self):
+        msg_text = '''\
+From: user@example.com
+To: other@example.com
+Subject: O, Romeo
+Message-Id: <capulet123@verona>
+
+Wherefore art thou?
+'''
+
+        msg = email.message_from_string(msg_text)
+        self.assertEqual(
+            distixlib.get_ids_from_message(msg), set(['capulet123@verona']))