Add MariaDB HTTP readiness service

tests/test_server.py

@@ -0,0 +1,29 @@
+import unittest
+from unittest.mock import MagicMock, patch
+
+import pymysql
+
+import server
+
+
+class DatabaseReadyTests(unittest.TestCase):
+    @patch("server.pymysql.connect")
+    def test_returns_true_for_select_one(self, connect):
+        connection = MagicMock()
+        cursor = connection.cursor.return_value
+        cursor.fetchone.return_value = (1,)
+        connect.return_value = connection
+
+        self.assertTrue(server.database_ready())
+        cursor.execute.assert_called_once_with("SELECT 1")
+        cursor.close.assert_called_once()
+        connection.close.assert_called_once()
+
+    @patch("server.pymysql.connect", side_effect=pymysql.MySQLError("unavailable"))
+    def test_returns_false_when_database_is_unavailable(self, connect):
+        self.assertFalse(server.database_ready())
+        connect.assert_called_once()
+
+
+if __name__ == "__main__":
+    unittest.main()