Simplify tests with data descriptors

Author: danny0838

Lib/test/test_zipfile/test_core.py

@@ -2503,11 +2503,14 @@ def _generate_local_file_entry(self, arcname, raw_bytes,
         fz = io.BytesIO()
         f = Unseekable(fz) if dd else fz
         cm = (mock.patch.object(struct, 'pack', side_effect=struct_pack_no_dd_sig)
-              if not dd_sig else contextlib.nullcontext())
+              if dd and not dd_sig else contextlib.nullcontext())
         with zipfile.ZipFile(f, 'w', compression=compression) as zh:
-            with cm:
-                with zh.open(arcname, 'w', force_zip64=force_zip64) as fh:
-                    fh.write(raw_bytes)
+            with cm, zh.open(arcname, 'w', force_zip64=force_zip64) as fh:
+                fh.write(raw_bytes)
+            if dd:
+                zi = zh.infolist()[0]
+                self.assertTrue(zi.flag_bits & zipfile._MASK_USE_DATA_DESCRIPTOR,
+                                f'data descriptor flag not set: {zi.filename}')
             fz.seek(0)
             return fz.read()
 

Lib/test/test_zipfile64.py

@@ -192,10 +192,6 @@ def _test_strip_removed_large_file_with_dd(self, f):
             zh.writestr(file, data)
 
         with zipfile.ZipFile(f, 'a') as zh:
-            # make sure data descriptor bit is really set (by making zip file unseekable)
-            for zi in zh.infolist():
-                self.assertTrue(zi.flag_bits & 8, f'data descriptor flag not set: {zi.filename}')
-
             zh.remove(file1)
             zh.repack()
             self.assertIsNone(zh.testzip())
@@ -227,10 +223,6 @@ def _test_strip_removed_large_file_with_dd_no_sig(self, f):
                 zh.writestr(file, data)
 
         with zipfile.ZipFile(f, 'a') as zh:
-            # make sure data descriptor bit is really set (by making zip file unseekable)
-            for zi in zh.infolist():
-                self.assertTrue(zi.flag_bits & 8, f'data descriptor flag not set: {zi.filename}')
-
             zh.remove(file1)
             zh.repack()
             self.assertIsNone(zh.testzip())
@@ -261,10 +253,6 @@ def _test_strip_removed_large_file_with_dd_no_sig_by_decompression(self, f, meth
                 zh.writestr(file, data)
 
         with zipfile.ZipFile(f, 'a') as zh:
-            # make sure data descriptor bit is really set (by making zip file unseekable)
-            for zi in zh.infolist():
-                self.assertTrue(zi.flag_bits & 8, f'data descriptor flag not set: {zi.filename}')
-
             zh.remove(file1)
             zh.repack()
             self.assertIsNone(zh.testzip())