3.9 initial support

.travis.yml

@@ -9,19 +9,19 @@ language: python
 
 matrix:
   include:
-    - python: "3.6"
-      env: TOXENV=py36
     - python: "3.7"
       env: TOXENV=py37
     - python: "3.8"
       env: TOXENV=py38
       dist: xenial
       sudo: true
+    - python: "3.9-dev"
+      env: TOXENV=py39
 
     # Meta
     - python: "3.8"
       env: TOXENV=lint
-    - python: "3.6"
+    - python: "3.8"
       env: TOXENV=docs
 
 before_install:

setup.py

@@ -49,8 +49,8 @@
         "License :: OSI Approved :: MIT License",
         "Natural Language :: English",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
     ],
 )

src/cattr/_compat.py

@@ -3,10 +3,13 @@
 from typing import (
     Dict,
     FrozenSet,
+    List,
     Mapping,
+    MutableMapping,
     MutableSequence,
     MutableSet,
     Sequence,
+    Set,
     Tuple,
 )
 
@@ -15,8 +18,14 @@
 is_py38 = version_info[:2] == (3, 8)
 
 
+def is_tuple(type):
+    return type is Tuple or (
+        type.__class__ is _GenericAlias and issubclass(type.__origin__, Tuple)
+    )
+
+
 if is_py37 or is_py38:
-    from typing import List, Union, _GenericAlias
+    from typing import Union, _GenericAlias
 
     def is_union_type(obj):
         return (
@@ -32,20 +41,14 @@ def is_sequence(type):
             and issubclass(type.__origin__, Sequence)
         )
 
-    def is_frozenset(type):
-        return type.__class__ is _GenericAlias and issubclass(
-            type.__origin__, FrozenSet
-        )
-
     def is_mutable_set(type):
         return type.__class__ is _GenericAlias and issubclass(
             type.__origin__, MutableSet
         )
 
-    def is_tuple(type):
-        return type is Tuple or (
-            type.__class__ is _GenericAlias
-            and issubclass(type.__origin__, Tuple)
+    def is_frozenset(type):
+        return type.__class__ is _GenericAlias and issubclass(
+            type.__origin__, FrozenSet
         )
 
     def is_mapping(type):
@@ -72,29 +75,51 @@ def is_bare(type):
 
 
 else:
-    from typing import _Union
+    # 3.9+
+    from typing import (
+        Union,
+        _GenericAlias,
+        _SpecialGenericAlias,
+        _UnionGenericAlias,
+    )
 
     def is_union_type(obj):
-        """Return true if the object is a union. """
-        return isinstance(obj, _Union)
-
-    def is_frozenset(type):
-        return issubclass(type, FrozenSet)
-
-    def is_mutable_set(type):
-        return issubclass(type, MutableSet)
+        return (
+            obj is Union
+            or isinstance(obj, _UnionGenericAlias)
+            and obj.__origin__ is Union
+        )
 
     def is_sequence(type):
-        is_string = issubclass(type, str)
-        return issubclass(type, Sequence) and not is_string
+        return (
+            type is List
+            or type is Sequence
+            or type is MutableSequence
+            or (
+                type.__class__ is _GenericAlias
+                and issubclass(type.__origin__, Sequence)
+            )
+        )
 
-    def is_tuple(type):
-        return issubclass(type, Tuple)
+    def is_mutable_set(type):
+        return type in (Set, MutableSet) or (
+            type.__class__ is _GenericAlias
+            and issubclass(type.__origin__, MutableSet)
+        )
 
-    def is_mapping(type):
-        return issubclass(type, Mapping)
+    def is_frozenset(type):
+        return type is FrozenSet or (
+            type.__class__ is _GenericAlias
+            and issubclass(type.__origin__, FrozenSet)
+        )
 
     def is_bare(type):
-        return not type.__args__
+        return isinstance(type, _SpecialGenericAlias) or (
+            not hasattr(type, "__origin__") and not hasattr(type, "__args__")
+        )
 
-    is_bare_frozenset = is_bare
+    def is_mapping(type):
+        return type in (Mapping, Dict, MutableMapping) or (
+            type.__class__ is _GenericAlias
+            and issubclass(type.__origin__, Mapping)
+        )

src/cattr/converters.py

@@ -113,7 +113,10 @@ def __init__(
         # Strings are sequences.
         self._structure_func.register_cls_list(
             [
-                (str, self._structure_call,),
+                (
+                    str,
+                    self._structure_call,
+                ),
                 (bytes, self._structure_call),
                 (int, self._structure_call),
                 (float, self._structure_call),
@@ -389,9 +392,12 @@ def _structure_union(self, obj, union):
         cl = self._dis_func_cache(union)(obj)
         return self._structure_func.dispatch(cl)(obj, cl)
 
-    def _structure_tuple(self, obj, tup):
+    def _structure_tuple(self, obj, tup: Type[T]):
         """Deal with converting to a tuple."""
-        tup_params = tup.__args__
+        if tup is Tuple:
+            tup_params = None
+        else:
+            tup_params = tup.__args__
         has_ellipsis = tup_params and tup_params[-1] is Ellipsis
         if tup_params is None or (has_ellipsis and tup_params[0] is Any):
             # Just a Tuple. (No generic information.)

tests/metadata/__init__.py

@@ -1,5 +1,6 @@
 """Tests for metadata functionality."""
 from collections import OrderedDict
+from typing import Any, Dict, List
 
 import attr
 from attr import NOTHING
@@ -15,8 +16,6 @@
     text,
     tuples,
 )
-from typing import Any, Dict, List
-from cattr._compat import unicode
 
 from .. import gen_attr_names, make_class
 
@@ -100,7 +99,7 @@ def str_typed_attrs(draw, defaults=None):
     default = NOTHING
     if defaults is True or (defaults is None and draw(booleans())):
         default = draw(text())
-    return (attr.ib(type=unicode, default=default), text())
+    return (attr.ib(type=str, default=default), text())
 
 
 @composite
@@ -125,7 +124,7 @@ def dict_typed_attrs(draw, defaults=None):
     val_strat = dictionaries(keys=text(), values=integers())
     if defaults is True or (defaults is None and draw(booleans())):
         default = draw(val_strat)
-    return (attr.ib(type=Dict[unicode, int], default=default), val_strat)
+    return (attr.ib(type=Dict[str, int], default=default), val_strat)
 
 
 def just_class(tup):

tests/metadata/test_roundtrips.py

@@ -52,7 +52,9 @@ def test_nested_roundtrip(cls_and_vals, strat):
     assert inst == converter.structure(converter.unstructure(inst), cl)
 
 
-@settings(suppress_health_check=[HealthCheck.filter_too_much])
+@settings(
+    suppress_health_check=[HealthCheck.filter_too_much, HealthCheck.too_slow]
+)
 @given(
     simple_typed_classes(defaults=False),
     simple_typed_classes(defaults=False),

tests/test_dict_generation.py

@@ -79,10 +79,17 @@ def test_nodefs_generated_unstructuring_cl(converter, cl_and_vals):
                 else:
                     assert attr.name in res
             else:
-                if val == attr.default.factory():
-                    assert attr.name not in res
+                # The default is a factory, but might take self.
+                if attr.default.takes_self:
+                    if val == attr.default.factory(cl):
+                        assert attr.name not in res
+                    else:
+                        assert attr.name in res
                 else:
-                    assert attr.name in res
+                    if val == attr.default.factory():
+                        assert attr.name not in res
+                    else:
+                        assert attr.name in res
 
 
 @given(nested_classes | simple_classes())
@@ -126,7 +133,13 @@ def test_individual_overrides(cl_and_vals):
                 else:
                     assert attr.name in res
             else:
-                if val == attr.default.factory():
-                    assert attr.name not in res
+                if attr.default.takes_self:
+                    if val == attr.default.factory(inst):
+                        assert attr.name not in res
+                    else:
+                        assert attr.name in res
                 else:
-                    assert attr.name in res
+                    if val == attr.default.factory():
+                        assert attr.name not in res
+                    else:
+                        assert attr.name in res