Refs #32061 -- Unified DatabaseClient.runshell() in db backends.

tests/backends/base/test_client.py

@@ -0,0 +1,16 @@
+from django.db import connection
+from django.db.backends.base.client import BaseDatabaseClient
+from django.test import SimpleTestCase
+
+
+class SimpleDatabaseClientTests(SimpleTestCase):
+    def setUp(self):
+        self.client = BaseDatabaseClient(connection=connection)
+
+    def test_settings_to_cmd_args_env(self):
+        msg = (
+            'subclasses of BaseDatabaseClient must provide a '
+            'settings_to_cmd_args_env() method or override a runshell().'
+        )
+        with self.assertRaisesMessage(NotImplementedError, msg):
+            self.client.settings_to_cmd_args_env(None, None)