fix dict_hash for None values; add more tests

Author: kmike

scrapy_splash/utils.py

@@ -40,6 +40,8 @@ def dict_hash(obj, start=''):
             value = str(obj)
         elif isinstance(obj, (six.text_type, bytes)):
             value = obj
+        elif obj is None:
+            value = b''
         else:
             raise ValueError("Unsupported value type: %s" % obj.__class__)
         h.update(to_bytes(value))

tests/test_utils.py

@@ -5,7 +5,12 @@
 from hypothesis import given, assume
 from hypothesis import strategies as st
 from scrapy.http import Headers
-from scrapy_splash.utils import headers_to_scrapy, _fast_hash, json_based_hash
+from scrapy_splash.utils import (
+    headers_to_scrapy,
+    _fast_hash,
+    json_based_hash,
+    dict_hash
+)
 
 
 def test_headers_to_scrapy():
@@ -56,6 +61,13 @@ def _dump(v):
     assert _fast_hash(val1) != _fast_hash(val2)
 
 
+@given(_data, _data)
+def test_dict_hash(val1, val2):
+    assume(val1 != val2)
+    assert dict_hash(val1) == dict_hash(val1)
+    assert dict_hash(val1) != dict_hash(val2)
+
+
 @given(_data_notuples, _data_notuples)
 def test_json_based_hash(val1, val2):
     assume(val1 != val2)