fix: handle None diffs in coverage change checks

Author: seer-by-sentry[bot]

services/notification/notifiers/comment/conditions.py

@@ -108,6 +108,8 @@ def _check_unexpected_changes(comparison: ComparisonProxy) -> bool:
     def _check_coverage_change(comparison: ComparisonProxy) -> bool:
         """Returns a bool that indicates wether there is any change in coverage"""
         diff = comparison.get_diff()
+        if diff is None:
+            return False
         res = comparison.head.report.calculate_diff(diff)
         return res is not None and res["general"].lines > 0
 
@@ -151,6 +153,8 @@ def _check_coverage_drop(comparison: ComparisonProxy) -> bool:
     @staticmethod
     def _check_uncovered_patch(comparison: ComparisonProxy) -> bool:
         diff = comparison.get_diff(use_original_base=True)
+        if diff is None:
+            return False
         totals = comparison.head.report.apply_diff(diff)
         coverage_not_affected_by_patch = totals and totals.lines == 0
         if totals is None or coverage_not_affected_by_patch:

tests/services/notification/notifiers/comment/test_conditions.py

@@ -0,0 +1,54 @@
+import unittest
+from decimal import Decimal
+from unittest.mock import MagicMock, patch
+
+from services.comparison import ComparisonProxy
+from services.notification.notifiers.base import AbstractBaseNotifier
+from services.notification.notifiers.comment.conditions import (
+    HasEnoughRequiredChanges,
+    NotifyCondition,
+)
+from shared.validation.types import CoverageCommentRequiredChanges
+
+
+class TestHasEnoughRequiredChanges(unittest.TestCase):
+    def setUp(self):
+        self.notifier = MagicMock(spec=AbstractBaseNotifier)
+        self.comparison = MagicMock(spec=ComparisonProxy)
+
+    def test_check_coverage_change_with_none_diff(self):
+        # Arrange
+        self.comparison.get_diff.return_value = None
+
+        # Act
+        result = HasEnoughRequiredChanges._check_coverage_change(self.comparison)
+
+        # Assert
+        self.assertFalse(result)
+        self.comparison.get_diff.assert_called_once()
+        self.comparison.head.report.calculate_diff.assert_not_called()
+
+    def test_check_uncovered_patch_with_none_diff(self):
+        # Arrange
+        self.comparison.get_diff.return_value = None
+
+        # Act
+        result = HasEnoughRequiredChanges._check_uncovered_patch(self.comparison)
+
+        # Assert
+        self.assertFalse(result)
+        self.comparison.get_diff.assert_called_once_with(use_original_base=True)
+        self.comparison.head.report.apply_diff.assert_not_called()
+
+    def test_check_any_change_with_none_diff(self):
+        # Arrange
+        self.comparison.get_diff.return_value = None
+        
+        # Mock _check_unexpected_changes to return False
+        with patch.object(HasEnoughRequiredChanges, '_check_unexpected_changes', return_value=False):
+            # Act
+            result = HasEnoughRequiredChanges._check_any_change(self.comparison)
+            
+            # Assert
+            self.assertFalse(result)
+            self.comparison.get_diff.assert_called_once()