Актализировал пакеты и структуру

tests/email_client/test_email_client.py

@@ -1,13 +1,12 @@
 import os
 from dotenv import load_dotenv
-import sys
-sys.path.append('./src')
-
-load_dotenv()
-
 from mail_order_bot.email_client import EmailClient
 
+
 if __name__ == "__main__":
+    # подгружаем переменные окружения
+    load_dotenv()
+
     email_client = EmailClient(
         imap_host=os.getenv('IMAP_HOST'),
         smtp_host=os.getenv('SMTP_HOST'),
@@ -17,6 +16,7 @@ if __name__ == "__main__":
         smtp_port=os.getenv('SMTP_PORT')
     )
     emails = email_client.get_emails(folder='spareparts', only_unseen=True, mark_as_read=True)
+
     for email in emails:
         print(email.subj)
         print(email.from_addr)