Mock smtplib to Test Patch Email Series in Python

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from unittest.mock import patch, Mock

def send_patch_series(subject_prefix, patches, smtp_host="localhost", smtp_port=25):
    """Simulate sending a series of patch emails."""
    for i, patch_content in enumerate(patches, start=1):
        msg = MIMEMultipart()
        msg["From"] = "sender@example.com"
        msg["To"] = "recipient@example.com"
        msg["Subject"] = f"{subject_prefix} [{i}/{len(patches)}]"
        msg.attach(MIMEText(patch_content, "plain"))

        with smtplib.SMTP(smtp_host, smtp_port) as server:
            server.send_message(msg)
            print(f"Sent: {msg['Subject']}")

def demo():
    patches = [
        "diff --git a/file1.py b/file1.py\n+def new_function():",
        "diff --git a/file2.py b/file2.py\n+class NewClass:",
        "diff --git a/file3.py b/file3.py\n+import new_module",
    ]

    fake_server = Mock()

    with patch("smtplib.SMTP", return_value=fake_server) as mock_smtp:
        send_patch_series("PATCH: feature-x", patches)

    print("\nSMTP called:", mock_smtp.call_count, "time(s)")
    print("send_message calls:", fake_server.send_message.call_count)

if __name__ == "__main__":
    demo()