bpo-42163, bpo-42189, bpo-42659: Support uname_tuple._replace (for all but processor) (#23010)

* Add test capturing missed expectation with uname_result._replace.

* bpo-42163: Override uname_result._make to allow uname_result._replace to work (for everything but 'processor'.

* Replace hard-coded length with one derived from the definition.

* Add test capturing missed expectation with copy/deepcopy on namedtuple (bpo-42189).

* bpo-42189: Exclude processor parameter when constructing uname_result.

* In _make, rely on __new__ to strip processor.

* Add blurb.

* iter is not necessary here.

* Rely on num_fields in __new__

* Add test for slices on uname

* Add test for copy and pickle.

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

* import pickle

* Fix equality test after pickling.

* Simply rely on __reduce__ for pickling.

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/Lib/platform.py b/Lib/platform.py
index 1a07b44..985e12d 100755
--- a/Lib/platform.py
+++ b/Lib/platform.py
@@ -769,7 +769,7 @@ class uname_result(
         ):
     """
     A uname_result that's largely compatible with a
-    simple namedtuple except that 'platform' is
+    simple namedtuple except that 'processor' is
     resolved late and cached to avoid calling "uname"
     except when needed.
     """
@@ -784,12 +784,25 @@ class uname_result(
             (self.processor,)
         )
 
+    @classmethod
+    def _make(cls, iterable):
+        # override factory to affect length check
+        num_fields = len(cls._fields)
+        result = cls.__new__(cls, *iterable)
+        if len(result) != num_fields + 1:
+            msg = f'Expected {num_fields} arguments, got {len(result)}'
+            raise TypeError(msg)
+        return result
+
     def __getitem__(self, key):
-        return tuple(iter(self))[key]
+        return tuple(self)[key]
 
     def __len__(self):
         return len(tuple(iter(self)))
 
+    def __reduce__(self):
+        return uname_result, tuple(self)[:len(self._fields)]
+
 
 _uname_cache = None