add email_login unit test

tests/metagpt/tools/libs/test_email_login.py

@@ -0,0 +1,50 @@
+import os
+from unittest.mock import Mock, patch
+
+import pytest
+
+from metagpt.tools.libs.email_login import email_login_imap
+
+# Configuration for the test IMAP servers
+TEST_IMAP_SERVERS = {"outlook.com": "imap-mail.outlook.com"}
+
+# Setup correct and incorrect email information
+correct_email_address = "englishgpt@outlook.com"
+correct_email_password = os.environ.get("outlook_email_password")
+incorrect_email_address = "test@unknown.com"
+incorrect_email_password = "incorrect_password"
+
+
+@pytest.fixture
+def imap_server_setup():
+    # Use patch to mock the behavior of MailBox from the correct module path
+    with patch("metagpt.tools.libs.email_login.MailBox") as mock_mailbox:
+        # Setup for successful login
+        mock_mail_instance = Mock()
+        mock_mail_instance.login.return_value = mock_mail_instance
+        mock_mailbox.return_value = mock_mail_instance
+        yield mock_mail_instance
+
+
+def test_email_login_imap_success(imap_server_setup):
+    # Mock successful login
+    mailbox = email_login_imap(correct_email_address, correct_email_password)
+    assert mailbox is not None
+    # Correctly assert that the login method of the MailBox mock was called with the correct arguments
+    imap_server_setup.login.assert_called_with(correct_email_address, correct_email_password)
+
+
+def test_email_login_imap_failure_due_to_incorrect_server(imap_server_setup):
+    # Attempt to login with an incorrect server
+    mailbox = email_login_imap(incorrect_email_address, incorrect_email_password)
+    assert mailbox is None
+
+
+def test_email_login_imap_failure_due_to_wrong_credentials(imap_server_setup):
+    # Configure mock to throw an exception to simulate login failure due to incorrect credentials
+    imap_server_setup.login.side_effect = Exception("Login failed")
+    # Attempt to login which should simulate a failure
+    mailbox = email_login_imap(correct_email_address, incorrect_email_password)
+    assert mailbox is None
+    # Verify that the login method was called with the expected arguments
+    imap_server_setup.login.assert_called_with(correct_email_address, incorrect_email_password)