Issue #25624: ZipFile now always writes a ZIP_STORED header for directory

entries.  Patch by Dingyuan Wang.

Lib/test/test_shutil.py

@@ -1105,6 +1105,29 @@ class TestShutil(unittest.TestCase):
             names2 = zf.namelist()
         self.assertEqual(sorted(names), sorted(names2))
 
+    @requires_zlib
+    @unittest.skipUnless(ZIP_SUPPORT, 'Need zip support to run')
+    @unittest.skipUnless(shutil.which('unzip'),
+                         'Need the unzip command to run')
+    def test_unzip_zipfile(self):
+        root_dir, base_dir = self._create_files()
+        base_name = os.path.join(self.mkdtemp(), 'archive')
+        archive = make_archive(base_name, 'zip', root_dir, base_dir)
+
+        # check if ZIP file  was created
+        self.assertEqual(archive, base_name + '.zip')
+        self.assertTrue(os.path.isfile(archive))
+
+        # now check the ZIP file using `unzip -t`
+        zip_cmd = ['unzip', '-t', archive]
+        with support.change_cwd(root_dir):
+            try:
+                subprocess.check_output(zip_cmd, stderr=subprocess.STDOUT)
+            except subprocess.CalledProcessError as exc:
+                details = exc.output.decode(errors="replace")
+                msg = "{}\n\n**Unzip Output**\n{}"
+                self.fail(msg.format(exc, details))
+
     def test_make_archive(self):
         tmpdir = self.mkdtemp()
         base_name = os.path.join(tmpdir, 'archive')

Lib/zipfile.py

@@ -1444,7 +1444,9 @@ class ZipFile:
             arcname += '/'
         zinfo = ZipInfo(arcname, date_time)
         zinfo.external_attr = (st[0] & 0xFFFF) << 16      # Unix attributes
-        if compress_type is None:
+        if isdir:
+            zinfo.compress_type = ZIP_STORED
+        elif compress_type is None:
             zinfo.compress_type = self.compression
         else:
             zinfo.compress_type = compress_type

Misc/ACKS

@@ -1518,6 +1518,7 @@ Richard Walker
 Larry Wall
 Kevin Walzer
 Rodrigo Steinmuller Wanderley
+Dingyuan Wang
 Ke Wang
 Greg Ward
 Tom Wardill

Misc/NEWS

@@ -77,6 +77,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #25624: ZipFile now always writes a ZIP_STORED header for directory
+  entries.  Patch by Dingyuan Wang.
+
 - Issue #25626: Change three zlib functions to accept sizes that fit in
   Py_ssize_t, but internally cap those sizes to UINT_MAX.  This resolves a
   regression in 3.5 where GzipFile.read() failed to read chunks larger than 2