Update unused-argument functional test

Update `unused-argument` test to include a check for the case of
`__init__` and `__new__` being defined in a class but `__new__` does not
use all of the argument. This is fine because `__new__` must have the
same argument of `__init__`.

Update with a second check in case of `__init__` being not defined in a
class. Then the unused arguments check must be done on `__new__`.

Author: Emplis

tests/functional/u/unused/unused_argument.py

@@ -107,3 +107,24 @@ class Descendant(Ancestor):
     def set_thing(self, thing, *, other=None):
         """Subclass does not raise unused-argument"""
         self.thing = thing
+
+
+# Test that Class with both `__init__` and `__new__` don't check
+# on `__new__` for unused arguments
+
+# pylint: disable=invalid-name
+
+class TestClassWithInitAndNew:
+    def __init__(self, argA, argB):
+        self.argA = argA
+        self.argB = argB
+
+    def __new__(cls, argA, argB):
+        return object.__new__(cls)
+
+# Test that `__new__` method is checked for unused arguments
+# when `__init__` is not in the Class
+
+class TestClassWithOnlyNew:
+    def __new__(cls, argA, argB): # [unused-argument, unused-argument]
+        return object.__new__(cls)

tests/functional/u/unused/unused_argument.txt

@@ -7,3 +7,5 @@ unused-argument:73:0:None:None:AAAA.selected:Unused argument 'args':INFERENCE
 unused-argument:73:0:None:None:AAAA.selected:Unused argument 'kwargs':INFERENCE
 unused-argument:92:23:92:26:BBBB.__init__:Unused argument 'arg':INFERENCE
 unused-argument:103:34:103:39:Ancestor.set_thing:Unused argument 'other':INFERENCE
+unused-argument:129:21:129:25:TestClassWithOnlyNew.__new__:Unused argument 'argA':INFERENCE
+unused-argument:129:27:129:31:TestClassWithOnlyNew.__new__:Unused argument 'argB':INFERENCE