Live server test case

[awdeorio]

It would be nice to add a small number of test cases that use a live SMTP server. At present, any non-dry-run test cases mock the STMP library calls.

Start an SMTP server in a separate process using a pytest fixture. Something roughly equivalent to this CLI: python -m smtpd -n -c DebuggingServer localhost:1025 . Then a test case would use a server config that connects to localhost:1025.

https://stackoverflow.com/questions/20349170/socket-error-errno-111-connection-refused