skip permission-related tests if the environment is not suitable

posix superuser can do anything on the filesystem

src/allmydata/test/cli/test_grid_manager.py

@@ -222,7 +222,8 @@ class GridManagerCommandLine(TestCase):
                 result.output,
             )
 
-    @skipIf(not platform.isLinux(), "I only know how permissions work on linux")
+    @skipIf(platform.isWindows(), "We don't know how to set permissions on Windows.")
+    @skipIf(os.getuid() == 0, "cannot test as superuser which all of the permissions")
     def test_sign_bad_perms(self):
         """
         Error reported if we can't create certificate file

src/allmydata/test/test_client.py

@@ -1,17 +1,7 @@
-"""
-Ported to Python 3.
-"""
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
-from future.utils import PY2
-if PY2:
-    from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401
+from __future__ import annotations
 
 import os
-import sys
+from unittest import skipIf
 from functools import (
     partial,
 )
@@ -42,6 +32,7 @@ from twisted.internet import defer
 from twisted.python.filepath import (
     FilePath,
 )
+from twisted.python.runtime import platform
 from testtools.matchers import (
     Equals,
     AfterPreprocessing,
@@ -156,12 +147,12 @@ class Basic(testutil.ReallyEqualMixin, unittest.TestCase):
                 yield client.create_client(basedir)
             self.assertIn("[client]helper.furl", str(ctx.exception))
 
-    def test_unreadable_config(self):
-        if sys.platform == "win32":
     # if somebody knows a clever way to do this (cause
     # EnvironmentError when reading a file that really exists), on
     # windows, please fix this
-            raise unittest.SkipTest("can't make unreadable files on windows")
+    @skipIf(platform.isWindows(), "We don't know how to set permissions on Windows.")
+    @skipIf(os.getuid() == 0, "cannot test as superuser which all of the permissions")
+    def test_unreadable_config(self):
         basedir = "test_client.Basic.test_unreadable_config"
         os.mkdir(basedir)
         fn = os.path.join(basedir, "tahoe.cfg")

src/allmydata/test/test_node.py

@@ -1,14 +1,4 @@
-"""
-Ported to Python 3.
-"""
-from __future__ import absolute_import
-from __future__ import division
-from __future__ import print_function
-from __future__ import unicode_literals
-
-from future.utils import PY2
-if PY2:
-    from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401
+from __future__ import annotations
 
 import base64
 import os
@@ -31,6 +21,7 @@ from unittest import skipIf
 from twisted.python.filepath import (
     FilePath,
 )
+from twisted.python.runtime import platform
 from twisted.trial import unittest
 from twisted.internet import defer
 
@@ -333,10 +324,8 @@ class TestCase(testutil.SignalMixin, unittest.TestCase):
         default = [("hello", "world")]
         self.assertEqual(config.items("nosuch", default), default)
 
-    @skipIf(
-        "win32" in sys.platform.lower() or "cygwin" in sys.platform.lower(),
-        "We don't know how to set permissions on Windows.",
-    )
+    @skipIf(platform.isWindows(), "We don't know how to set permissions on Windows.")
+    @skipIf(os.getuid() == 0, "cannot test as superuser which all of the permissions")
     def test_private_config_unreadable(self):
         """
         Asking for inaccessible private config is an error
@@ -351,10 +340,8 @@ class TestCase(testutil.SignalMixin, unittest.TestCase):
         with self.assertRaises(Exception):
             config.get_or_create_private_config("foo")
 
-    @skipIf(
-        "win32" in sys.platform.lower() or "cygwin" in sys.platform.lower(),
-        "We don't know how to set permissions on Windows.",
-    )
+    @skipIf(platform.isWindows(), "We don't know how to set permissions on Windows.")
+    @skipIf(os.getuid() == 0, "cannot test as superuser which all of the permissions")
     def test_private_config_unreadable_preexisting(self):
         """
         error if reading private config data fails
@@ -411,6 +398,7 @@ class TestCase(testutil.SignalMixin, unittest.TestCase):
         self.assertEqual(len(counter), 1) # don't call unless necessary
         self.assertEqual(value, "newer")
 
+    @skipIf(os.getuid() == 0, "cannot test as superuser which all of the permissions")
     def test_write_config_unwritable_file(self):
         """
         Existing behavior merely logs any errors upon writing