re-export NoReturn as Never instead of using type alias

KotlinIsland · Jan 8, 2022 · 5bb187b · 5bb187b
1 parent 156f5bd
commit 5bb187b
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Showing 3 changed files with 19 additions and 20 deletions.
diff --git a/basedtyping/__init__.py b/basedtyping/__init__.py
@@ -6,6 +6,7 @@
     TYPE_CHECKING,
     Callable,
     Generic,
+    NoReturn as Never,
     Protocol,
     Sequence,
     TypeVar,
@@ -14,11 +15,11 @@
     cast,
 )
 
-# TODO: use typing.NoReturn once https://github.com/python/mypy/issues/11903 is in basedmypy
-from mypy_extensions import NoReturn
-
 from basedtyping.runtime_only import OldUnionType
 
+# prevent no-implicit-reexport mypy error
+__all__ = ["Never"]
+
 if TYPE_CHECKING:
     Function = Callable[..., object]  # type: ignore[misc]
     """Any ``Callable``. useful when using mypy with ``disallow-any-explicit``
@@ -31,10 +32,6 @@
     # for isinstance checks
     Function = Callable
 
-
-Never = NoReturn
-"""a type that can never exist. this is the narrowest possible type"""
-
 # Unlike the generics in other modules, these are meant to be imported to save you from the boilerplate
 
 T = TypeVar("T")

diff --git a/pyproject.toml b/pyproject.toml
@@ -57,14 +57,16 @@ disable = [
     "missing-function-docstring",
     "missing-module-docstring",
     "missing-class-docstring",
-    "invalid-name",               # https://github.com/PyCQA/pylint/issues/3401
+    "invalid-name",                              # https://github.com/PyCQA/pylint/issues/3401
     "fixme",
-    "useless-import-alias",       # required when using no-implicit-reexport in mypy
-    "no-member",                  # handled by mypy
-    "inherit-non-class",          # handled by mypy, false positive on ReifiedGeneric
+    "useless-import-alias",                      # required when using no-implicit-reexport in mypy
+    "no-member",                                 # handled by mypy
+    "inherit-non-class",                         # handled by mypy, false positive on ReifiedGeneric
     "too-few-public-methods",
-    "unused-import",              # false negatives + handled by flake8
-    "duplicate-code",             # https://github.com/PyCQA/pylint/issues/214
+    "unused-import",                             # false negatives + handled by flake8
+    "duplicate-code",                            # https://github.com/PyCQA/pylint/issues/214
+    "isinstance-second-argument-not-valid-type", # false positive on Never type, handled by mypy
+    "no-value-for-parameter",                    # handled by mypy
 ]
 enable = ["useless-suppression", "deprecated-pragma"]
 

diff --git a/tests/test_never_type/test_runtime.py b/tests/test_never_type/test_runtime.py
@@ -2,29 +2,29 @@
 
 from basedtyping import Never, issubform
 
+# xfail tests due to https://github.com/KotlinIsland/basedmypy/issues/24
 
+
+@mark.xfail
 def test_isinstance() -> None:
-    # https://github.com/python/mypy/issues/11903
-    assert not isinstance(  # type:ignore[misc]
+    assert not isinstance(
         1,
         # https://github.com/KotlinIsland/basedmypy/issues/136
         Never,  # type:ignore[arg-type]
     )
 
 
-# https://github.com/python/mypy/issues/11903 and/or https://github.com/KotlinIsland/basedmypy/issues/24
 @mark.xfail
 def test_issubform_true() -> None:
     """https://github.com/KotlinIsland/basedtyping/issues/22"""
-    assert issubform(Never, int)  # type:ignore[arg-type]
+    assert issubform(Never, int)
 
 
+@mark.xfail
 def test_issubform_false() -> None:
-    assert not issubform(str, Never)  # type:ignore[arg-type]
+    assert not issubform(str, Never)
 
 
-@mark.xfail
 def test_cant_instanciate() -> None:
-    """https://github.com/python/mypy/issues/11903"""
     with raises(TypeError):
         Never()  # type:ignore[operator]