Merge pull request #8782 from Couchers-org/backend/bugfix/check-config-stale-keys

Backend: add check_config coverage for stale config key references

Author: aapeliv

app/backend/src/couchers/config.py

@@ -168,10 +168,6 @@ def check_config(cfg: dict[str, Any]) -> None:
         if not cfg["RECAPTHCA_PROJECT_ID"] or not cfg["RECAPTHCA_API_KEY"] or not cfg["RECAPTHCA_SITE_KEY"]:
             raise Exception("reCAPTCHA credentials must be configured in production")
 
-    if cfg["ENABLE_DONATIONS"]:
-        if not cfg["STRIPE_API_KEY"] or not cfg["STRIPE_WEBHOOK_SECRET"] or not cfg["STRIPE_RECURRING_PRODUCT_ID"]:
-            raise Exception("No Stripe API key/recurring donation ID but donations enabled")
-
     if cfg["EXPERIMENTATION_ENABLED"]:
         if not cfg["GROWTHBOOK_CLIENT_KEY"]:
             raise Exception("No GrowthBook client key but experimentation enabled")

app/backend/src/tests/test_config.py

@@ -0,0 +1,44 @@
+from typing import Any
+
+import pytest
+
+from couchers.config import CONFIG_OPTIONS, check_config
+
+
+def _complete_config(dev: bool) -> dict[str, Any]:
+    """Build a config dict with every CONFIG_OPTIONS key populated with a valid, truthy value.
+
+    This mirrors what make_config() produces when every env var is set, so check_config() must be
+    able to run against it without touching any key outside CONFIG_OPTIONS.
+    """
+    cfg: dict[str, Any] = {}
+    for name, type_, *_ in CONFIG_OPTIONS:
+        if type_ is bool:
+            cfg[name] = True
+        elif type_ is int:
+            cfg[name] = 1
+        elif type_ is bytes:
+            cfg[name] = b"x"
+        elif isinstance(type_, list):
+            cfg[name] = type_[0]
+        else:
+            cfg[name] = "x"
+
+    cfg["DEV"] = dev
+    if not dev:
+        # production invariants that aren't satisfiable by a generic truthy value
+        cfg["BASE_URL"] = "https://example.com"
+        cfg["ENABLE_EMAIL"] = True
+        cfg["IN_TEST"] = False
+    return cfg
+
+
+@pytest.mark.parametrize("dev", [True, False])
+def test_check_config_only_references_known_keys(dev):
+    """check_config() must only access config keys that are declared in CONFIG_OPTIONS.
+
+    A reference to a key that was removed from CONFIG_OPTIONS (e.g. a toggle migrated to a feature
+    flag) would raise KeyError at app boot but is invisible to the rest of the test suite, since
+    check_config() only runs in app.py's startup path. Exercising it here catches that.
+    """
+    check_config(_complete_config(dev=dev))