red-mail/redmail/test/email/test_cookbook.py

from typing import Union
from redmail import EmailSender

def test_distributions():
    class DistrSender(EmailSender):
        "Send email using pre-defined distribution lists"

        def __init__(self, *args, distribution:dict, **kwargs):
            super().__init__(*args, **kwargs)
            self.distributions = distribution

        def get_receivers(self, receiver_list):
            if receiver_list:
                return self.distributions[receiver_list]

        def get_cc(self, receiver_list):
            if receiver_list:
                return self.distributions[receiver_list]

        def get_bcc(self, receiver_list):
            if receiver_list:
                return self.distributions[receiver_list]

    email = DistrSender(
        host="localhost", 
        port=0,
        distribution={
            'group1': ["me@example.com", "you@example.com"],
            'group2': ["he@example.com", "she@example.com"],
        }
    )

    msg = email.get_message(
        sender="me@example.com",
        receivers="group1",
        cc="group2",
        subject="Some email",
    )
    assert dict(msg.items()) == {
        'from': 'me@example.com', 
        'subject': 'Some email', 
        'to': 'me@example.com, you@example.com', 
        'cc': 'he@example.com, she@example.com', 
    }