Move dotdot_resolves_early setting to setUpClass

Author: encukou

Lib/test/test_tarfile.py

@@ -3682,6 +3682,39 @@ class TestExtractionFilters(unittest.TestCase):
     # The destination for the extraction, within `outerdir`
     destdir = outerdir / 'dest'
 
+    @classmethod
+    def setUpClass(cls):
+        # Posix and Windows have different pathname resolution:
+        # either symlink or a '..' component resolve first.
+        # Let's see which we are on.
+        if os_helper.can_symlink():
+            testpath = os.path.join(TEMPDIR, 'resolution_test')
+            os.mkdir(testpath)
+
+            # testpath/current links to `.` which is all of:
+            #   - `testpath`
+            #   - `testpath/current`
+            #   - `testpath/current/current`
+            #   - etc.
+            os.symlink('.', os.path.join(testpath, 'current'))
+
+            # we'll test where `testpath/current/../file` ends up
+            with open(os.path.join(testpath, 'current', '..', 'file'), 'w'):
+                pass
+
+            if os.path.exists(os.path.join(testpath, 'file')):
+                # Windows collapses 'current\..' to '.' first, leaving
+                # 'testpath\file'
+                cls.dotdot_resolves_early = True
+            elif os.path.exists(os.path.join(testpath, '..', 'file')):
+                # Posix resolves 'current' to '.' first, leaving
+                # 'testpath/../file'
+                cls.dotdot_resolves_early = False
+            else:
+                raise AssertionError('Could not determine link resolution')
+        else:
+            cls.dotdot_resolves_early = False
+
     @contextmanager
     def check_context(self, tar, filter, *, check_flag=True):
         """Extracts `tar` to `self.destdir` and allows checking the result
@@ -3955,35 +3988,6 @@ def test_parent_symlink2(self):
         # Test interplaying symlinks
         # Inspired by 'dirsymlink2b' in jwilk/traversal-archives
 
-        # Posix and Windows have different pathname resolution:
-        # either symlink or a '..' component resolve first.
-        # Let's see which we are on.
-        if os_helper.can_symlink():
-            testpath = os.path.join(TEMPDIR, 'resolution_test')
-            os.mkdir(testpath)
-
-            # testpath/current links to `.` which is all of:
-            #   - `testpath`
-            #   - `testpath/current`
-            #   - `testpath/current/current`
-            #   - etc.
-            os.symlink('.', os.path.join(testpath, 'current'))
-
-            # we'll test where `testpath/current/../file` ends up
-            with open(os.path.join(testpath, 'current', '..', 'file'), 'w'):
-                pass
-
-            if os.path.exists(os.path.join(testpath, 'file')):
-                # Windows collapses 'current\..' to '.' first, leaving
-                # 'testpath\file'
-                dotdot_resolves_early = True
-            elif os.path.exists(os.path.join(testpath, '..', 'file')):
-                # Posix resolves 'current' to '.' first, leaving
-                # 'testpath/../file'
-                dotdot_resolves_early = False
-            else:
-                raise AssertionError('Could not determine link resolution')
-
         with ArchiveMaker() as arc:
 
             # `current` links to `.` which is both the destination directory
@@ -4019,7 +4023,7 @@ def test_parent_symlink2(self):
 
         with self.check_context(arc.open(), 'data'):
             if os_helper.can_symlink():
-                if dotdot_resolves_early:
+                if self.dotdot_resolves_early:
                     # Fail when extracting a file outside destination
                     self.expect_exception(
                             tarfile.OutsideDestinationError,