Fix #525 -- Unpack SQL arguments

Fix a TypeError when calling cursor.execute, we need to pass
the query as attributes not as a single tuple.

Author: codingjoe

health_check/contrib/db_heartbeat/backends.py

@@ -23,7 +23,7 @@ def check_status(self):
             result = None
             compiler = connection.ops.compiler("SQLCompiler")(SelectOne(), connection, None)
             with connection.cursor() as cursor:
-                cursor.execute(compiler.compile(SelectOne()))
+                cursor.execute(*compiler.compile(SelectOne()))
                 result = cursor.fetchone()
 
             if result != (1,):

tests/test_db_heartbeat.py

@@ -1,6 +1,8 @@
 import unittest
 from unittest.mock import MagicMock, patch
 
+import pytest
+
 from health_check.contrib.db_heartbeat.backends import DatabaseHeartBeatCheck, SelectOne
 from health_check.exceptions import ServiceUnavailable
 
@@ -20,8 +22,13 @@ def test_as_oracle(self):
 
 
 class TestDatabaseHeartBeatCheck(unittest.TestCase):
+    @pytest.mark.django_db
+    def test_check_status__success(self):
+        health_check = DatabaseHeartBeatCheck()
+        health_check.check_status()
+
     @patch("health_check.contrib.db_heartbeat.backends.connection")
-    def test_check_status_success(self, mock_connection):
+    def test_check_status__failure(self, mock_connection):
         mock_cursor = MagicMock()
         mock_cursor.fetchone.return_value = (1,)
         mock_connection.cursor.return_value.__enter__.return_value = mock_cursor