security: enhance API key redaction with comprehensive testing and error handling

- Refactored redaction logic to use centralized helper function
- Added robust error handling in AccessLogFormatter
- Improved regex patterns for better OpenAI key detection
- Added comprehensive unit tests covering edge cases and error scenarios
- Enhanced input validation with descriptive error placeholders

tests/__init__.py

@@ -0,0 +1 @@
+# Tests package

tests/test_key_redaction.py

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+"""
+Unit tests for API key redaction functionality
+"""
+
+import unittest
+import logging
+from unittest.mock import patch, MagicMock
+
+from app.utils.helpers import redact_key_for_logging
+from app.log.logger import AccessLogFormatter
+
+
+class TestKeyRedaction(unittest.TestCase):
+    """Test cases for the redact_key_for_logging function"""
+
+    def test_valid_long_key_redaction(self):
+        """Test redaction of valid long API keys"""
+        # Test Google/Gemini API key
+        # This value is a random generated string for testing
+        gemini_key = "AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI"
+        result = redact_key_for_logging(gemini_key)
+        expected = "AIzaSy...xDfGhI"
+        self.assertEqual(result, expected)
+
+        # Test OpenAI API key
+        # This value is a random generated string for testing
+        openai_key = "sk-1234567890abcdef1234567890abcdef1234567890abcdef"
+        result = redact_key_for_logging(openai_key)
+        expected = "sk-123...abcdef"
+        self.assertEqual(result, expected)
+
+    def test_short_key_handling(self):
+        """Test handling of short keys"""
+        short_key = "short"
+        result = redact_key_for_logging(short_key)
+        self.assertEqual(result, "[SHORT_KEY]")
+
+        # Test exactly 12 characters (boundary case)
+        boundary_key = "123456789012"
+        result = redact_key_for_logging(boundary_key)
+        self.assertEqual(result, "[SHORT_KEY]")
+
+    def test_empty_and_none_keys(self):
+        """Test handling of empty and None keys"""
+        # Test empty string
+        result = redact_key_for_logging("")
+        self.assertEqual(result, "[INVALID_KEY]")
+
+        # Test None
+        result = redact_key_for_logging(None)
+        self.assertEqual(result, "[INVALID_KEY]")
+
+    def test_invalid_input_types(self):
+        """Test handling of invalid input types"""
+        # Test integer
+        result = redact_key_for_logging(123)
+        self.assertEqual(result, "[INVALID_KEY]")
+
+        # Test list
+        result = redact_key_for_logging(["key"])
+        self.assertEqual(result, "[INVALID_KEY]")
+
+        # Test dict
+        result = redact_key_for_logging({"key": "value"})
+        self.assertEqual(result, "[INVALID_KEY]")
+
+    def test_boundary_cases(self):
+        """Test boundary cases for key length"""
+        # Test 13 characters (just above the threshold)
+        key_13 = "1234567890123"
+        result = redact_key_for_logging(key_13)
+        expected = "123456...890123"
+        self.assertEqual(result, expected)
+
+        # Test very long key
+        long_key = "a" * 100
+        result = redact_key_for_logging(long_key)
+        expected = "aaaaaa...aaaaaa"
+        self.assertEqual(result, expected)
+
+
+class TestAccessLogFormatter(unittest.TestCase):
+    """Test cases for the AccessLogFormatter class"""
+
+    def setUp(self):
+        """Set up test fixtures"""
+        self.formatter = AccessLogFormatter()
+
+    def test_gemini_key_redaction_in_url(self):
+        """Test redaction of Gemini API keys in URLs"""
+        log_message = (
+            'POST /verify-key/AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI HTTP/1.1" 200'
+        )
+        result = self.formatter._redact_api_keys_in_message(log_message)
+        self.assertIn("AIzaSy...xDfGhI", result)
+        self.assertNotIn("AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI", result)
+
+    def test_openai_key_redaction_in_url(self):
+        """Test redaction of OpenAI API keys in URLs"""
+        log_message = 'GET /api/models?key=sk-1234567890abcdef1234567890abcdef1234567890abcdef HTTP/1.1" 200'
+        result = self.formatter._redact_api_keys_in_message(log_message)
+        self.assertIn("sk-123...abcdef", result)
+        self.assertNotIn("sk-1234567890abcdef1234567890abcdef1234567890abcdef", result)
+
+    def test_multiple_keys_in_message(self):
+        """Test redaction of multiple API keys in a single message"""
+        log_message = "Request with keys: AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI and sk-1234567890abcdef1234567890abcdef1234567890abcdef"
+        result = self.formatter._redact_api_keys_in_message(log_message)
+        self.assertIn("AIzaSy...xDfGhI", result)
+        self.assertIn("sk-123...abcdef", result)
+        self.assertNotIn("AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI", result)
+        self.assertNotIn("sk-1234567890abcdef1234567890abcdef1234567890abcdef", result)
+
+    def test_no_keys_in_message(self):
+        """Test that messages without API keys are unchanged"""
+        log_message = 'GET /api/health HTTP/1.1" 200'
+        result = self.formatter._redact_api_keys_in_message(log_message)
+        self.assertEqual(result, log_message)
+
+    def test_partial_key_patterns_not_redacted(self):
+        """Test that partial key patterns are not redacted"""
+        log_message = "Message with partial patterns: AIza sk- incomplete"
+        result = self.formatter._redact_api_keys_in_message(log_message)
+        self.assertEqual(result, log_message)
+
+    def test_error_handling_in_redaction(self):
+        """Test error handling in the redaction process"""
+        # Test by directly calling _redact_api_keys_in_message with a broken pattern
+        original_patterns = self.formatter.compiled_patterns
+        # Create a mock pattern that will raise an exception
+        mock_pattern = MagicMock()
+        mock_pattern.sub.side_effect = Exception("Regex error")
+        self.formatter.compiled_patterns = [mock_pattern]
+
+        try:
+            log_message = (
+                'POST /verify-key/AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI HTTP/1.1" 200'
+            )
+            result = self.formatter._redact_api_keys_in_message(log_message)
+            self.assertEqual(result, "[LOG_REDACTION_ERROR]")
+        finally:
+            # Restore original patterns
+            self.formatter.compiled_patterns = original_patterns
+
+    def test_format_method(self):
+        """Test the format method of AccessLogFormatter"""
+        # Create a mock log record
+        record = MagicMock()
+        record.getMessage.return_value = (
+            'POST /verify-key/AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI HTTP/1.1" 200'
+        )
+
+        # Mock the parent format method
+        with patch(
+            "logging.Formatter.format",
+            return_value='2025-01-01 12:00:00 | INFO | POST /verify-key/AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI HTTP/1.1" 200',
+        ):
+            result = self.formatter.format(record)
+            self.assertIn("AIzaSy...xDfGhI", result)
+            self.assertNotIn("AIzaSyDhKGfJ8xYzQwErTyUiOpLkMnBvCxDfGhI", result)
+
+    def test_regex_patterns_compilation(self):
+        """Test that regex patterns are properly compiled"""
+        formatter = AccessLogFormatter()
+        self.assertEqual(len(formatter.compiled_patterns), 2)
+        self.assertTrue(
+            all(hasattr(pattern, "sub") for pattern in formatter.compiled_patterns)
+        )
+
+    def test_flexible_openai_pattern(self):
+        """Test the flexible OpenAI pattern matches various formats"""
+        test_cases = [
+            "sk-1234567890abcdef1234567890abcdef1234567890abcdef",  # Standard 48 chars
+            "sk-proj-1234567890abcdef1234567890abcdef1234567890abcdef",  # Project key
+            "sk-1234567890abcdef_1234567890abcdef-1234567890abcdef",  # With underscores/hyphens
+            "sk-12345678901234567890",  # Shorter key (20 chars)
+        ]
+
+        for test_key in test_cases:
+            log_message = f"Request with key: {test_key}"
+            result = self.formatter._redact_api_keys_in_message(log_message)
+            self.assertNotIn(test_key, result)
+            self.assertIn("sk-", result)  # Should still contain the prefix
+
+
+if __name__ == "__main__":
+    unittest.main()