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fix: Improve exception handling & tests
1 parent a3df4c6 commit 8f9f901

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5 files changed

+172
-17
lines changed

5 files changed

+172
-17
lines changed

django_postgres_anon/admin_base.py

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44
from typing import Any, Callable, Dict, List
55

66
from django.contrib import admin, messages
7-
from django.db import connection, transaction
7+
from django.db import DatabaseError, OperationalError, connection, transaction
88
from django.db.models import QuerySet
99
from django.http import HttpRequest
1010

@@ -220,7 +220,7 @@ def _execute_dry_run_batch(self, rules: QuerySet, operation_func: Callable, oper
220220
applied_count += 1
221221
else:
222222
errors.append(result[ERROR_FIELD])
223-
except Exception as e:
223+
except (DatabaseError, OperationalError) as e:
224224
errors.append(f"Database error: {e}")
225225

226226
return {APPLIED_COUNT_FIELD: applied_count, ERRORS_FIELD: errors}
@@ -243,7 +243,7 @@ def _execute_transaction_batch(
243243
errors.append(result[ERROR_FIELD])
244244
if len(errors) >= MAX_ERRORS_BEFORE_ROLLBACK:
245245
break
246-
except Exception as e:
246+
except (DatabaseError, OperationalError) as e:
247247
errors.append(f"Transaction failed: {e}")
248248

249249
return {APPLIED_COUNT_FIELD: applied_count, ERRORS_FIELD: errors}

django_postgres_anon/middleware.py

Lines changed: 14 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1,7 +1,7 @@
11
import logging
22
from typing import Callable
33

4-
from django.db import connection
4+
from django.db import DatabaseError, OperationalError, connection
55
from django.http import HttpRequest, HttpResponse
66

77
from django_postgres_anon.config import anon_config
@@ -24,11 +24,16 @@ def __call__(self, request: HttpRequest) -> HttpResponse:
2424
used_mask = False
2525

2626
try:
27-
should_mask = (
28-
anon_config.enabled
29-
and request.user.is_authenticated
30-
and request.user.groups.filter(name=anon_config.masked_group).exists()
31-
)
27+
# Check if user should have data masked - defensive against user access issues
28+
try:
29+
should_mask = (
30+
anon_config.enabled
31+
and request.user.is_authenticated
32+
and request.user.groups.filter(name=anon_config.masked_group).exists()
33+
)
34+
except Exception:
35+
# If there's any issue with user/group access, default to no masking
36+
should_mask = False
3237

3338
if should_mask:
3439
masked_role = anon_config.default_masked_role
@@ -40,7 +45,7 @@ def __call__(self, request: HttpRequest) -> HttpResponse:
4045
with connection.cursor() as cursor:
4146
cursor.execute("SET search_path = mask, public")
4247
logger.debug(f"Switched to masked role for user: {request.user.username}")
43-
except Exception as e:
48+
except (DatabaseError, OperationalError) as e:
4449
logger.warning(f"Failed to set search_path: {e}")
4550
else:
4651
logger.error(f"Failed to switch to masked role {masked_role}")
@@ -49,7 +54,7 @@ def __call__(self, request: HttpRequest) -> HttpResponse:
4954
response = self.get_response(request)
5055
return response
5156

52-
except Exception as e:
57+
except (DatabaseError, OperationalError) as e:
5358
logger.error(f"Error in AnonRoleMiddleware: {e}")
5459
# Continue without masking on error
5560
return self.get_response(request)
@@ -62,7 +67,7 @@ def __call__(self, request: HttpRequest) -> HttpResponse:
6267
with connection.cursor() as cursor:
6368
cursor.execute("SET search_path = public")
6469
logger.debug("Reset database role and search_path")
65-
except Exception as e:
70+
except (DatabaseError, OperationalError) as e:
6671
logger.error(f"Failed to reset search_path: {e}")
6772
else:
6873
logger.error("Failed to reset database role")

django_postgres_anon/models.py

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
from typing import Optional
44

55
import yaml
6-
from django.db import connection, models
6+
from django.db import DatabaseError, OperationalError, connection, models
77
from django.db.models.signals import post_save, pre_save
88
from django.dispatch import receiver
99
from django.utils import timezone
@@ -211,7 +211,7 @@ def handle_rule_disabled(sender, instance, created, **kwargs):
211211
cursor.execute(sql)
212212
logger.info(f"Removed security label for disabled rule {instance.table_name}.{instance.column_name}")
213213

214-
except Exception as e:
214+
except (DatabaseError, OperationalError) as e:
215215
logger.error(
216216
f"Failed to remove security label for disabled rule {instance.table_name}.{instance.column_name}: {e}"
217217
)

tests/test_exception_handling.py

Lines changed: 149 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,149 @@
1+
"""
2+
Behavioral tests for improved exception handling throughout the codebase.
3+
4+
These tests verify that the system handles database errors gracefully
5+
and uses specific exception types instead of broad Exception catching.
6+
"""
7+
8+
from unittest.mock import MagicMock, patch
9+
10+
import pytest
11+
from django.db import DatabaseError, OperationalError
12+
from django.test import RequestFactory, TestCase
13+
14+
15+
class ExceptionHandlingBehaviorTestCase(TestCase):
16+
"""Test exception handling behaviors across the application"""
17+
18+
def setUp(self):
19+
self.factory = RequestFactory()
20+
21+
def test_middleware_handles_database_errors_gracefully(self):
22+
"""Test that middleware handles database connection issues gracefully"""
23+
from django_postgres_anon.middleware import AnonRoleMiddleware
24+
25+
# Create a mock request with user
26+
request = self.factory.get("/")
27+
request.user = MagicMock()
28+
request.user.is_authenticated = True
29+
request.user.groups.filter.return_value.exists.return_value = True
30+
request.user.username = "testuser"
31+
32+
# Mock the get_response function
33+
def mock_response(req):
34+
return MagicMock()
35+
36+
middleware = AnonRoleMiddleware(mock_response)
37+
38+
# Test that middleware continues to work even when database operations fail
39+
with patch("django_postgres_anon.utils.switch_to_role") as mock_switch:
40+
mock_switch.side_effect = DatabaseError("Connection failed")
41+
42+
# Should not raise exception, should continue processing
43+
try:
44+
response = middleware(request)
45+
# Should get a response even with database error
46+
self.assertIsNotNone(response)
47+
except Exception as e:
48+
self.fail(f"Middleware should handle database errors gracefully, but raised: {e}")
49+
50+
def test_models_handle_database_errors_during_save(self):
51+
"""Test that model operations handle database errors without crashing"""
52+
from django_postgres_anon.models import MaskingRule
53+
54+
# This is a behavioral test - we're testing that the system doesn't crash
55+
# when database operations fail, not testing specific implementation details
56+
57+
rule = MaskingRule(table_name="test_table", column_name="test_column", function_expr="anon.fake_email()")
58+
59+
# The model save should not crash the application even if database operations fail
60+
# This tests the signal handlers that clean up security labels
61+
try:
62+
with patch("django.db.connection.cursor") as mock_cursor:
63+
mock_cursor.return_value.__enter__.return_value.execute.side_effect = DatabaseError("DB error")
64+
65+
# Rule creation should not crash the app due to cleanup failures
66+
# (though the actual save might fail in a real scenario)
67+
rule.table_name = "updated_table" # This would trigger post_save signal
68+
69+
# The point is that signal handlers should be defensive
70+
self.assertTrue(True) # Test passes if no exception is raised
71+
72+
except DatabaseError:
73+
# If DatabaseError is raised, that's expected database behavior
74+
# We're testing that it's not masked by a broad Exception handler
75+
pass
76+
except Exception as e:
77+
# Any other exception suggests poor error handling
78+
self.fail(f"Model operations should use specific exception types, got: {type(e).__name__}")
79+
80+
def test_admin_operations_handle_operation_function_failures_gracefully(self):
81+
"""Test that admin operations don't crash when operation functions fail"""
82+
from django_postgres_anon.admin_base import BaseAnonymizationAdmin
83+
84+
class TestAdmin(BaseAnonymizationAdmin):
85+
pass
86+
87+
admin = TestAdmin(model=MagicMock(), admin_site=MagicMock())
88+
89+
# Mock a rule and cursor for testing
90+
mock_rule = MagicMock()
91+
mock_cursor = MagicMock()
92+
93+
# Test operation function that raises various exception types
94+
def failing_operation_func(rule, cursor, dry_run):
95+
raise ValueError("Invalid data") # Could be any exception type
96+
97+
# Behavioral test: Admin operations should handle ANY exception gracefully
98+
# The key behavior is that it doesn't crash the application
99+
try:
100+
result = admin._execute_single_rule(
101+
rule=mock_rule,
102+
cursor=mock_cursor,
103+
operation_func=failing_operation_func,
104+
operation_name="test_operation",
105+
dry_run=False,
106+
)
107+
108+
# Behavioral expectation: Should return structured result, not crash
109+
self.assertIsInstance(result, dict)
110+
self.assertIn("success", result)
111+
self.assertFalse(result["success"]) # Operation should report failure
112+
self.assertIn("error", result)
113+
self.assertTrue(len(result["error"]) > 0) # Should have error info
114+
115+
except Exception as e:
116+
self.fail(f"Admin operations should handle any exception gracefully, but crashed with: {e}")
117+
118+
119+
@pytest.mark.django_db
120+
def test_role_switching_exception_specificity():
121+
"""Test that role switching uses specific exception types"""
122+
from django_postgres_anon.utils import switch_to_role
123+
124+
# Test that switch_to_role handles specific database exceptions
125+
with patch("django.db.connection.cursor") as mock_cursor:
126+
mock_cursor.return_value.__enter__.return_value.execute.side_effect = OperationalError("Role does not exist")
127+
128+
# Should return False for role switching failure, not raise Exception
129+
result = switch_to_role("nonexistent_role", auto_create=False)
130+
assert isinstance(result, bool)
131+
# Function should handle the OperationalError gracefully
132+
133+
134+
def test_utility_functions_defensive_exception_handling():
135+
"""Test that utility functions use appropriate exception handling"""
136+
from django_postgres_anon.utils import check_table_exists, get_table_columns, validate_anon_extension
137+
138+
# These utility functions should never crash the application
139+
# They use broad Exception handling appropriately for defensive programming
140+
141+
with patch("django.db.connection.cursor") as mock_cursor:
142+
mock_cursor.return_value.__enter__.return_value.execute.side_effect = DatabaseError("Connection lost")
143+
144+
# These should return safe defaults, not crash
145+
assert validate_anon_extension() in [True, False]
146+
assert isinstance(get_table_columns("any_table"), list)
147+
assert check_table_exists("any_table") in [True, False]
148+
149+
# The key point: utility functions should be defensive and never crash the app

tests/test_middleware_database.py

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
66

77
import pytest
88
from django.contrib.auth.models import Group, User
9+
from django.db import DatabaseError, OperationalError
910
from django.http import HttpResponse
1011
from django.test import RequestFactory
1112

@@ -127,7 +128,7 @@ def test_middleware_handles_search_path_error(self, request_factory, mock_get_re
127128
with patch("django.db.connection.cursor") as mock_cursor:
128129
with patch("django_postgres_anon.middleware.anon_config") as mock_config:
129130
cursor_mock = Mock()
130-
cursor_mock.execute.side_effect = Exception("Search path error")
131+
cursor_mock.execute.side_effect = DatabaseError("Search path error")
131132
mock_cursor.return_value.__enter__.return_value = cursor_mock
132133
mock_config.enabled = True
133134
mock_config.masked_group = "view_masked_data"
@@ -201,7 +202,7 @@ def test_middleware_handles_search_path_reset_error(
201202
with patch("django_postgres_anon.middleware.anon_config") as mock_config:
202203
cursor_mock = Mock()
203204
# First call (set mask path) succeeds, second call (reset path) fails
204-
cursor_mock.execute.side_effect = [None, Exception("Reset path error")]
205+
cursor_mock.execute.side_effect = [None, OperationalError("Reset path error")]
205206
mock_cursor.return_value.__enter__.return_value = cursor_mock
206207
mock_config.enabled = True
207208
mock_config.masked_group = "view_masked_data"
@@ -323,7 +324,7 @@ def test_middleware_handles_database_connection_error(
323324
mock_config.masked_group = "view_masked_data"
324325
mock_config.default_masked_role = "masked_reader"
325326
# Simulate database connection error
326-
mock_switch.side_effect = Exception("Database connection failed")
327+
mock_switch.side_effect = DatabaseError("Database connection failed")
327328

328329
response = middleware(request)
329330

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