Add "reply" filter (#465)

* Add "reply" filter

This filter will filter messages that reply to other's message.

* Add test for "reply" filter

* Add "Kjwon15" to AUTHORS.rst

AUTHORS.rst

@@ -20,6 +20,7 @@ The following wonderful people contributed directly or indirectly to this projec
 - `jh0ker <https://github.com/jh0ker>`_
 - `JRoot3D <https://github.com/JRoot3D>`_
 - `jlmadurga <https://github.com/jlmadurga>`_
+- `Kjwon15 <https://github.com/kjwon15>`_
 - `Li-aung Yip <https://github.com/LiaungYip>`_
 - `macrojames <https://github.com/macrojames>`_
 - `Michael Elovskikh <https://github.com/wronglink>`_

telegram/ext/filters.py

@@ -107,6 +107,13 @@ class Filters(object):
         def filter(self, message):
             return bool(message.text and message.text.startswith('/'))
 
+    class _Reply(BaseFilter):
+
+        def filter(self, message):
+            return bool(message.reply_to_message)
+
+    reply = _Reply()
+
     command = _Command()
 
     class _Audio(BaseFilter):

tests/test_filters.py

@@ -51,6 +51,14 @@ class FiltersTest(BaseTest, unittest.TestCase):
         self.message.text = '/test'
         self.assertTrue(Filters.command(self.message))
 
+    def test_filters_reply(self):
+        another_message = Message(1, User(1, "TestOther"), datetime.now(), Chat(0, 'private'))
+        self.message.text = 'test'
+        self.assertFalse(Filters.reply(self.message))
+        self.assertFalse(Filters.reply(Filters.message))
+        self.message.reply_to_message = another_message
+        self.assertTrue(Filters.reply(self.message))
+
     def test_filters_audio(self):
         self.message.audio = 'test'
         self.assertTrue(Filters.audio(self.message))