diff --git a/tests/test_extra_fields.py b/tests/test_extra_fields.py
new file mode 100644
index 0000000..4a332a7
--- /dev/null
+++ b/tests/test_extra_fields.py
@@ -0,0 +1,86 @@
+import fnmatch
+import logging.config
+import os
+import time
+import json
+from unittest import TestCase
+from logzio.handler import ExtraFieldsLogFilter
+from .mockLogzioListener import listener
+
+
+def _find(pattern, path):
+    result = []
+    for root, dirs, files in os.walk(path):
+        for name in files:
+            if fnmatch.fnmatch(name, pattern):
+                result.append(os.path.join(root, name))
+
+        break  # Not descending recursively
+    return result
+
+
+class TestExtraFieldsFilter(TestCase):
+
+    def setUp(self):
+        self.logzio_listener = listener.MockLogzioListener()
+        self.logzio_listener.clear_logs_buffer()
+        self.logzio_listener.clear_server_error()
+        self.logs_drain_timeout = 1
+        self.retries_no = 4
+        self.retry_timeout = 2
+        self.add_context = True
+        logging_configuration = {
+            "version": 1,
+            "formatters": {
+                "logzio": {
+                    "format": '{"key": "value"}',
+                    "validate": False
+                }
+            },
+            "handlers": {
+                "LogzioHandler": {
+                    "class": "logzio.handler.LogzioHandler",
+                    "formatter": "logzio",
+                    "level": "DEBUG",
+                    "token": "token",
+                    'logzio_type': "type",
+                    'logs_drain_timeout': self.logs_drain_timeout,
+                    'url': "http://" + self.logzio_listener.get_host() + ":" + str(self.logzio_listener.get_port()),
+                    'debug': True,
+                    'retries_no': self.retries_no,
+                    'retry_timeout': self.retry_timeout,
+                    'add_context': self.add_context
+                }
+            },
+            "loggers": {
+                "test": {
+                    "handlers": ["LogzioHandler"],
+                    "level": "DEBUG"
+                }
+            }
+        }
+
+        logging.config.dictConfig(logging_configuration)
+        self.logger = logging.getLogger('test')
+
+        for curr_file in _find("logzio-failures-*.txt", "."):
+            os.remove(curr_file)
+
+    def test_add_extra_fields(self):
+        extra_fields = {"foo": "bar"}
+        self.logger.addFilter(ExtraFieldsLogFilter(extra=extra_fields))
+        log_message = "this log should have a additional fields"
+        self.logger.info(log_message)
+        time.sleep(self.logs_drain_timeout * 2)
+        logs_list = self.logzio_listener.logs_list
+        for current_log in logs_list:
+            if log_message in current_log:
+                log_dict = json.loads(current_log)
+                try:
+                    self.assertEqual(extra_fields, {**extra_fields,**log_dict})
+                except AssertionError as err:
+                    print(err)
+
+
+if __name__ == '__main__':
+    unittest.main()