Instantiate config when needed and support optional env vars

Author: ghukill

carbon/config.py

@@ -18,7 +18,8 @@ class Config:
         "WORKSPACE",
     )
     OPTIONAL_ENVIRONMENT_VARIABLES: Iterable[str] = ("ARTICLES_PUBLISH_DAYS_PAST",)
-    ARTICLES_PUBLISH_DAYS_PAST: str
+
+    ARTICLES_PUBLISH_DAYS_PAST: str | None = None
     FEED_TYPE: str
     CONNECTION_STRING: str
     SYMPLECTIC_FTP_USER: str

carbon/feed.py

@@ -1,4 +1,3 @@
-import os
 from abc import ABC, abstractmethod
 from collections.abc import Generator
 from contextlib import closing
@@ -17,8 +16,6 @@
     get_initials,
 )
 
-config = Config()
-
 
 class BaseXmlFeed(ABC):
     """Base XML feed class.
@@ -121,6 +118,8 @@ def query(self) -> Select:  # type: ignore[override]
         be in the future, so an article may be included multiple times in the XML output
         until its future date has passed.
         """
+        config = Config()
+
         query_object = (
             select(aa_articles)
             .where(aa_articles.c.ARTICLE_ID.is_not(None))
@@ -129,11 +128,11 @@ def query(self) -> Select:  # type: ignore[override]
             .where(aa_articles.c.MIT_ID.is_not(None))
         )
 
-        if days_past := os.environ.get("ARTICLES_PUBLISH_DAYS_PAST"):
+        if config.ARTICLES_PUBLISH_DAYS_PAST:
             query_object = query_object.where(
                 text(
                     "TO_DATE(PUBLISH_DATE, 'MM/DD/YYYY') >= "
-                    f"SYSDATE - {int(days_past)}"
+                    f"SYSDATE - {int(config.ARTICLES_PUBLISH_DAYS_PAST)}"
                 )
             )
 

tests/conftest.py

@@ -41,7 +41,7 @@ def _test_env(ftp_server, monkeypatch):
             '"SYMPLECTIC_FTP_PASS": "pass"}'
         ),
     )
-    monkeypatch.delenv("ARTICLES_PUBLISH_DAYS_PAST")
+    monkeypatch.delenv("ARTICLES_PUBLISH_DAYS_PAST", raising=False)
 
 
 @pytest.fixture(autouse=True)