Fix too strict regex for pecentage style logging

Regression introduced in 0055dc5.

Only fields followed by an 's' were correctly extracted.
As there are other possible cases like '8s', 'd', or no 's' at all the regex is
loosened.

In this funky case "[%(levelname)8s][PID %(process)d][%(threadName)s]"
the extracted field was "levelname)8s][PID %(process)d][%(threadName".

Author: aberres

src/pythonjsonlogger/jsonlogger.py

@@ -146,15 +146,15 @@ def parse(self) -> List[str]:
 
         This method is responsible for returning a list of fields (as strings)
         to include in all log messages.
-        """        
+        """
         if isinstance(self._style, logging.StringTemplateStyle):
             formatter_style_pattern = re.compile(r'\$\{(.+?)\}', re.IGNORECASE)
         elif isinstance(self._style, logging.StrFormatStyle):
             formatter_style_pattern = re.compile(r'\{(.+?)\}', re.IGNORECASE)
         # PercentStyle is parent class of StringTemplateStyle and StrFormatStyle so
         # it needs to be checked last.
         elif isinstance(self._style, logging.PercentStyle):
-            formatter_style_pattern = re.compile(r'%\((.+?)\)s', re.IGNORECASE)
+            formatter_style_pattern = re.compile(r'%\((.+?)\)', re.IGNORECASE)
         else:
             raise ValueError('Invalid format: %s' % self._fmt)
 

tests/tests.py

@@ -42,6 +42,20 @@ def testDefaultFormat(self):
 
         self.assertEqual(logJson["message"], msg)
 
+    def testPercentageFormat(self):
+        fr = jsonlogger.JsonFormatter(
+            # All kind of different styles to check the regex
+            '[%(levelname)8s] %(message)s %(filename)s:%(lineno)d %(asctime)'
+        )
+        self.logHandler.setFormatter(fr)
+
+        msg = "testing logging format"
+        self.logger.info(msg)
+        logJson = json.loads(self.buffer.getvalue())
+
+        self.assertEqual(logJson["message"], msg)
+        self.assertEqual(logJson.keys(), {'levelname', 'message', 'filename', 'lineno', 'asctime'})
+
     def testRenameBaseField(self):
         fr = jsonlogger.JsonFormatter(rename_fields={'message': '@message'})
         self.logHandler.setFormatter(fr)