Add type annotations to tests

Also, switch from tmpdir to tmp_path, as the former uses a deprecated
path library.

tests/src/test_checks.py

@@ -46,7 +46,7 @@ class ChildOfBadClass(BadInheritAndOverlap):
 
 
 class _RestrictiveMeta(type):
-    def __setattr__(self, name, value) -> None:
+    def __setattr__(self, name: str, value: object) -> None:
         raise TypeError("BOOM!")
 
 
@@ -83,13 +83,13 @@ class TestHasSlots:
         "klass",
         [type, dict, date, float, Decimal, Element, array],
     )
-    def test_not_purepython(self, klass):
+    def test_not_purepython(self, klass: type) -> None:
         assert has_slots(klass)
 
-    def test_typeddict(self):
+    def test_typeddict(self) -> None:
         assert has_slots(MyDict)
 
-    def test_typing_extensions_typeddict(self):
+    def test_typing_extensions_typeddict(self) -> None:
         assert has_slots(MyTypingExtensionsTypedDict)
 
     @pytest.mark.parametrize(
@@ -106,7 +106,7 @@ def test_typing_extensions_typeddict(self):
             FooMeta,
         ],
     )
-    def test_slots(self, klass):
+    def test_slots(self, klass: type) -> None:
         assert has_slots(klass)
 
     @pytest.mark.parametrize(
@@ -120,10 +120,10 @@ def test_slots(self, klass):
             KeyboardInterrupt,
         ],
     )
-    def test_no_slots(self, klass):
+    def test_no_slots(self, klass: type) -> None:
         assert not has_slots(klass)
 
-    def test_immutable_class(self):
+    def test_immutable_class(self) -> None:
         assert not has_slots(_UnsettableClass)
 
 
@@ -132,7 +132,7 @@ class TestSlotsOverlap:
         "klass",
         [type, dict, date, float, Decimal, AssertionError, RuntimeError],
     )
-    def test_not_purepython(self, klass):
+    def test_not_purepython(self, klass: type) -> None:
         assert not slots_overlap(klass)
 
     @pytest.mark.parametrize(
@@ -148,17 +148,17 @@ def test_not_purepython(self, klass):
             ArrayInherit,
         ],
     )
-    def test_slots_ok(self, klass):
+    def test_slots_ok(self, klass: type) -> None:
         assert not slots_overlap(klass)
 
     @pytest.mark.parametrize("klass", [BadOverlaps, BadInheritAndOverlap])
-    def test_slots_not_ok(self, klass):
+    def test_slots_not_ok(self, klass: type) -> None:
         assert slots_overlap(klass)
 
     @pytest.mark.parametrize(
         "klass", [Random, Enum, NoSlotsInherits, ChildOfBadClass]
     )
-    def test_no_slots(self, klass):
+    def test_no_slots(self, klass: type) -> None:
         assert not slots_overlap(klass)
 
 
@@ -167,22 +167,22 @@ class TestHasSlotlessBase:
         "klass",
         [type, dict, date, float, Decimal],
     )
-    def test_not_purepython(self, klass):
+    def test_not_purepython(self, klass: type) -> None:
         assert not has_slotless_base(klass)
 
     @pytest.mark.parametrize(
         "klass", [Fraction, HasSlots, GoodInherit, BadOverlaps, OneStringSlot]
     )
-    def test_slots_ok(self, klass):
+    def test_slots_ok(self, klass: type) -> None:
         assert not has_slotless_base(klass)
 
     @pytest.mark.parametrize(
         "klass",
         [BadInherit, BadInheritAndOverlap, AssertionError, RuntimeError],
     )
-    def test_slots_not_ok(self, klass):
+    def test_slots_not_ok(self, klass: type) -> None:
         assert has_slotless_base(klass)
 
     @pytest.mark.parametrize("klass", [Enum, NoSlotsInherits, ChildOfBadClass])
-    def test_no_slots(self, klass):
+    def test_no_slots(self, klass: type) -> None:
         assert not has_slotless_base(klass)