Fix #96 -- Override contect manager to lazy open SMTP connections (#100)

emark/backends.py

@@ -16,6 +16,13 @@
 
 
 class RenderEmailBackendMixin:
+
+    def __enter__(self):
+        # Do not open a connection before rendering the messages
+        # to avoid connection timeouts.
+        # EmailBackend.send_messages() will open the connection.
+        return self
+
     def send_messages(self, email_messages):
         for message in email_messages:
             if isinstance(message, MarkdownEmail):
@@ -26,6 +33,12 @@ def send_messages(self, email_messages):
 class TrackingEmailBackendMixin:
     """Add a tracking framework to an email backend."""
 
+    def __enter__(self):
+        # Do not open a connection before rendering the messages
+        # to avoid connection timeouts.
+        # EmailBackend.send_messages() will open the connection.
+        return self
+
     def send_messages(self, email_messages):
         self._messages_sent = []
         for message in email_messages:

tests/test_backends.py

@@ -27,6 +27,11 @@ def test_write_message__multipart(self):
 
 
 class TestSMTPEmailBackend:
+
+    def test_enter(self):
+        with backends.SMTPEmailBackend() as backend:
+            assert not backend.connection, "Connection should not be opened"
+
     def test_send(self, email_message):
         class TestBackend(backends.SMTPEmailBackend):
             def _send(self, message):
@@ -103,6 +108,11 @@ def test_write_message__native_email__multiple_recipients(self):
 
 
 class TestTrackingSMTPEmailBackend:
+
+    def test_enter(self):
+        with backends.TrackingSMTPEmailBackend() as backend:
+            assert not backend.connection, "Connection should not be opened"
+
     @pytest.mark.django_db
     def test_send(self, email_message):
         email_message.to = [