Test the new decoder with hypothesis.

Author: Lukasa

test/test_huffman.py

@@ -1,8 +1,12 @@
 # -*- coding: utf-8 -*-
+from hpack.exceptions import HPACKDecodingError
 from hpack.huffman_table import decode_huffman
 from hpack.huffman import HuffmanEncoder
 from hpack.huffman_constants import REQUEST_CODES, REQUEST_CODES_LENGTH
 
+from hypothesis import given, example
+from hypothesis.strategies import binary
+
 
 class TestHuffman(object):
 
@@ -18,3 +22,24 @@ def test_request_huffman_encode(self):
         assert encoder.encode(b"no-cache") == b'\xa8\xeb\x10d\x9c\xbf'
         assert encoder.encode(b"custom-key") == b'%\xa8I\xe9[\xa9}\x7f'
         assert encoder.encode(b"custom-value") == b'%\xa8I\xe9[\xb8\xe8\xb4\xbf'
+
+
+class TestHuffmanDecoder(object):
+    @given(data=binary())
+    @example(b'\xff')
+    @example(b'\x5f\xff\xff\xff\xff')
+    @example(b'\x00\x3f\xff\xff\xff')
+    def test_huffman_decoder_properly_handles_all_bytestrings(self, data):
+        """
+        When given random bytestrings, either we get HPACKDecodingError or we
+        get a bytestring back.
+        """
+        # The examples aren't special, they're just known to hit specific error
+        # paths through the state machine. Basically, they are strings that are
+        # definitely invalid.
+        try:
+            result = decode_huffman(data)
+        except HPACKDecodingError:
+            result = b''
+
+        assert isinstance(result, bytes)