Fix typing coverage (#2032)

* fix coverage

* linting

* correct forward ref import

* fix conlist __args__

* chore: remove useless except

* skip test_get_args prior to 3.8

Co-authored-by: PrettyWood <em.jolibois@gmail.com>

pydantic/types.py

@@ -15,6 +15,7 @@ from typing import (
     Optional,
     Pattern,
     Set,
+    Tuple,
     Type,
     TypeVar,
     Union,
@@ -132,7 +133,7 @@ T = TypeVar('T')
 class ConstrainedList(list):  # type: ignore
     # Needed for pydantic to detect that this is a list
     __origin__ = list
-    __args__: List[Type[T]]  # type: ignore
+    __args__: Tuple[Type[T], ...]  # type: ignore
 
     min_items: Optional[int] = None
     max_items: Optional[int] = None
@@ -165,7 +166,7 @@ class ConstrainedList(list):  # type: ignore
 
 def conlist(item_type: Type[T], *, min_items: int = None, max_items: int = None) -> Type[List[T]]:
     # __args__ is needed to conform to typing generics api
-    namespace = {'min_items': min_items, 'max_items': max_items, 'item_type': item_type, '__args__': [item_type]}
+    namespace = {'min_items': min_items, 'max_items': max_items, 'item_type': item_type, '__args__': (item_type,)}
     # We use new_class to be able to deal with Generic types
     return new_class('ConstrainedListValue', (ConstrainedList,), {}, lambda ns: ns.update(namespace))
 

pydantic/typing.py

@@ -124,12 +124,8 @@ else:
             get_args(Union[int, Tuple[T, int]][str]) == (int, Tuple[str, int])
             get_args(Callable[[], T][int]) == ([], int)
         """
-        try:
-            args = typing_get_args(tp)
-        except IndexError:
-            args = ()
         # the fallback is needed for the same reasons as `get_origin` (see above)
-        return args or getattr(tp, '__args__', ()) or generic_get_args(tp)
+        return typing_get_args(tp) or getattr(tp, '__args__', ()) or generic_get_args(tp)
 
 
 if TYPE_CHECKING:

tests/test_utils.py

@@ -1,18 +1,28 @@
 import os
 import re
 import string
+import sys
 from copy import copy, deepcopy
 from distutils.version import StrictVersion
 from enum import Enum
-from typing import NewType, Union
+from typing import Callable, Dict, List, NewType, Tuple, TypeVar, Union
 
 import pytest
 
-from pydantic import VERSION, BaseModel
+from pydantic import VERSION, BaseModel, ConstrainedList, conlist
 from pydantic.color import Color
 from pydantic.dataclasses import dataclass
 from pydantic.fields import Undefined
-from pydantic.typing import Literal, all_literal_values, display_as_type, is_new_type, new_type_supertype
+from pydantic.typing import (
+    ForwardRef,
+    Literal,
+    all_literal_values,
+    display_as_type,
+    get_args,
+    is_new_type,
+    new_type_supertype,
+    resolve_annotations,
+)
 from pydantic.utils import (
     BUILTIN_COLLECTIONS,
     ClassAttribute,
@@ -409,3 +419,30 @@ def test_smart_deepcopy_collection(collection, mocker):
     expected_value = object()
     mocker.patch('pydantic.utils.deepcopy', return_value=expected_value)
     assert smart_deepcopy(collection) is expected_value
+
+
+T = TypeVar('T')
+
+
+@pytest.mark.skipif(sys.version_info < (3, 8), reason='get_args is only consistent for python >= 3.8')
+@pytest.mark.parametrize(
+    'input_value,output_value',
+    [
+        (conlist(str), (str,)),
+        (ConstrainedList, ()),
+        (List[str], (str,)),
+        (Dict[str, int], (str, int)),
+        (int, ()),
+        (Union[int, Union[T, int], str][int], (int, str)),
+        (Union[int, Tuple[T, int]][str], (int, Tuple[str, int])),
+        (Callable[[], T][int], ([], int)),
+    ],
+)
+def test_get_args(input_value, output_value):
+    assert get_args(input_value) == output_value
+
+
+def test_resolve_annotations_no_module():
+    # TODO: is there a better test for this, can this case really happen?
+    fr = ForwardRef('Foo')
+    assert resolve_annotations({'Foo': ForwardRef('Foo')}, None) == {'Foo': fr}