refactor: attachments default to empty list/dict

emailer_lib/structs.py

@@ -1,5 +1,5 @@
 from __future__ import annotations
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 import re
 
 from email.message import EmailMessage
@@ -62,10 +62,10 @@ class IntermediateEmail:
     rsc_email_supress_scheduled: bool | None = None
 
     # is a list of files in path from current directory
-    external_attachments: list[str] | None = None
+    external_attachments: list[str] = field(default_factory=list)
 
     # has structure {filename: base64_string}
-    inline_attachments: dict[str, str] | None = None
+    inline_attachments: dict[str, str] = field(default_factory=dict)
 
     text: str | None = None  # sometimes present in quarto
     recipients: list[str] | None = None  # not present in quarto

emailer_lib/tests/test_structs.py

@@ -27,8 +27,8 @@ def test_creation_without_text_and_attachments():
     )
     assert email.text is None
     assert email.recipients is None
-    assert email.external_attachments is None
-    assert email.inline_attachments is None
+    assert email.external_attachments == []
+    assert email.inline_attachments == {}
     assert email.subject == "No Text or Attachments"
 
 
@@ -94,4 +94,4 @@ def test_not_implemented_methods(method_name):
     )
     method = getattr(email, method_name)
     with pytest.raises(NotImplementedError):
-        method()
+        method()