Issue 6877 - Only parse headers in the first line of the filter list

tests/test_rpy.py

 # This file is part of Adblock Plus <https://adblockplus.org/>,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ skipping 13 matching lines @@
 
 
 _SAMPLE_TUPLE = namedtuple('tuple', 'foo,bar')
 
 _TEST_EXAMPLES = {
     'header': {
         'in': b'[Adblock Plus 2.0]',
         'out': {
             b'type': b'Header',
             b'version': b'Adblock Plus 2.0',
+        },
+    },
+    'metadata': {
+        'in': b'! Title: Example list',
+        'out': {
+            b'type': b'Metadata',
+            b'key': b'Title',
+            b'value': b'Example list',
         },
     },
     'comment': {
         'in': b'! Comment',
         'out': {
             b'type': b'Comment',
             b'text': b'Comment',
         },
     },
     'empty': {
@@ skipping 84 matching lines @@
     data = line2dict(_TEST_EXAMPLES[line_type]['in'])
     check_data_utf8(data)
 
 
 @pytest.mark.parametrize('line_type', list(_TEST_EXAMPLES.keys()))
 def test_line2dict_format(line_type):
     """Test that the API result has the appropriate format.
 
     Checks for both keys and datatypes.
     """
-    mode = 'start' if line_type == 'header' else 'body'
-    data = line2dict(_TEST_EXAMPLES[line_type]['in'], mode)
+    position = 'start' if line_type in {'header', 'metadata'} else 'body'
+    data = line2dict(_TEST_EXAMPLES[line_type]['in'], position)
 
     assert data == _TEST_EXAMPLES[line_type]['out']