diff --git a/tests/test_handler.py b/tests/test_handler.py
new file mode 100644
index 0000000..7a960d5
--- /dev/null
+++ b/tests/test_handler.py
@@ -0,0 +1,37 @@
+import unittest
+
+from handler import MixinHandler
+
+
+class RequestMock(object):
+
+    def __init__(self):
+        self.headers = {}
+
+    def set_ip(self, ip):
+        self.headers['X-Real-Ip'] = ip
+
+    def set_port(self, port):
+        self.headers['X-Real-Port'] = port
+
+
+class TestMixinHandler(unittest.TestCase):
+
+    def test_get_real_client_addr(self):
+        handler = MixinHandler()
+        handler.request = RequestMock()
+        self.assertIsNone(handler.get_real_client_addr())
+
+        ip = '127.0.0.1'
+        handler.request.set_ip(ip)
+        with self.assertLogs() as cm:
+            handler.get_real_client_addr()
+        self.assertEqual(cm.output, ['WARNING:root:Bad nginx configuration.'])
+
+        handler.request.set_port('12345x')
+        with self.assertLogs() as cm:
+            handler.get_real_client_addr()
+        self.assertEqual(cm.output, ['WARNING:root:Bad nginx configuration.'])
+
+        handler.request.set_port('12345')
+        self.assertEqual(handler.get_real_client_addr(), (ip, 12345))