Make the serializer behave like a normal func with unknown kwargs

html5lib/serializer/htmlserializer.py

@@ -155,6 +155,9 @@ def __init__(self, **kwargs):
 
         .. _html5lib user documentation: http://code.google.com/p/html5lib/wiki/UserDocumentation
         """
+        unexpected_args = frozenset(kwargs) - frozenset(self.options)
+        if len(unexpected_args) > 0:
+            raise TypeError("__init__() got an unexpected keyword argument '%s'" % next(iter(unexpected_args)))
         if 'quote_char' in kwargs:
             self.use_best_quote_char = False
         for attr in self.options:

html5lib/tests/test_serializer.py

@@ -79,9 +79,12 @@ def _convertAttrib(self, attribs):
 
 def serialize_html(input, options):
     options = dict([(str(k), v) for k, v in options.items()])
+    encoding = options.get("encoding", None)
+    if "encoding" in options:
+        del options["encoding"]
     stream = Lint(JsonWalker(input), False)
     serializer = HTMLSerializer(alphabetical_attributes=True, **options)
-    return serializer.render(stream, options.get("encoding", None))
+    return serializer.render(stream, encoding)
 
 
 def runSerializerTest(input, expected, options):
@@ -146,6 +149,11 @@ def testComment():
     throwsWithLatin1([["Comment", "\u0101"]])
 
 
+def testThrowsUnknownOption():
+    with pytest.raises(TypeError):
+        HTMLSerializer(foobar=None)
+
+
 @pytest.mark.parametrize("c", list("\t\n\u000C\x20\r\"'=<>`"))
 def testSpecQuoteAttribute(c):
     input_ = [["StartTag", "http://www.w3.org/1999/xhtml", "span",