fix: harden state corp exchange imports

tests/apps/core/test_startup_checks.py

@@ -0,0 +1,38 @@
+"""Tests for fail-fast dependency checks."""
+
+from __future__ import annotations
+
+from unittest.mock import MagicMock, patch
+
+from apps.core.startup_checks import _check_db
+from django.test import SimpleTestCase
+
+
+class DatabaseStartupCheckTest(SimpleTestCase):
+    """Require a Unicode-safe PostgreSQL database before startup."""
+
+    @staticmethod
+    def _connection_with_encoding(encoding: str) -> MagicMock:
+        connection = MagicMock()
+        cursor = connection.cursor.return_value.__enter__.return_value
+        cursor.fetchone.side_effect = [(1,), (encoding,)]
+        return connection
+
+    @patch("apps.core.startup_checks.psycopg2.connect")
+    def test_check_db_accepts_utf8_database(self, connect):
+        connect.return_value = self._connection_with_encoding("UTF8")
+
+        ok, message = _check_db(timeout_seconds=3)
+
+        self.assertTrue(ok)
+        self.assertEqual(message, "OK")
+
+    @patch("apps.core.startup_checks.psycopg2.connect")
+    def test_check_db_rejects_non_utf8_database(self, connect):
+        connect.return_value = self._connection_with_encoding("SQL_ASCII")
+
+        ok, message = _check_db(timeout_seconds=3)
+
+        self.assertFalse(ok)
+        self.assertIn("database encoding SQL_ASCII is unsupported", message)
+        self.assertIn("UTF8 is required", message)