Write long description in message payload

changelog.d/2628.change.rst

@@ -0,0 +1 @@
+Write long description in message payload of PKG-INFO file. - by :user:`cdce8p`

setuptools/dist.py

@@ -92,6 +92,13 @@ def _read_list_from_msg(msg: "Message", field: str) -> Optional[List[str]]:
     return values
 
 
+def _read_payload_from_msg(msg: "Message") -> Optional[str]:
+    value = msg.get_payload().strip()
+    if value == 'UNKNOWN':
+        return None
+    return value
+
+
 def read_pkg_file(self, file):
     """Reads the metadata values from a file object."""
     msg = message_from_file(file)
@@ -114,6 +121,8 @@ def read_pkg_file(self, file):
         self.download_url = None
 
     self.long_description = _read_field_unescaped_from_msg(msg, 'description')
+    if self.long_description is None and self.metadata_version >= StrictVersion('2.1'):
+        self.long_description = _read_payload_from_msg(msg)
     self.description = _read_field_from_msg(msg, 'summary')
 
     if 'keywords' in msg:
@@ -176,9 +185,6 @@ def write_field(key, value):
     for project_url in self.project_urls.items():
         write_field('Project-URL', '%s, %s' % project_url)
 
-    long_desc = rfc822_escape(self.get_long_description())
-    write_field('Description', long_desc)
-
     keywords = ','.join(self.get_keywords())
     if keywords:
         write_field('Keywords', keywords)
@@ -207,6 +213,8 @@ def write_field(key, value):
         for extra in self.provides_extras:
             write_field('Provides-Extra', extra)
 
+    file.write("\n%s\n\n" % self.get_long_description())
+
 
 sequence = tuple, list
 

setuptools/tests/test_dist.py

@@ -251,8 +251,8 @@ def test_maintainer_author(name, attrs, tmpdir):
     with io.open(str(fn.join('PKG-INFO')), 'r', encoding='utf-8') as f:
         raw_pkg_lines = f.readlines()
 
-    # Drop blank lines
-    pkg_lines = list(filter(None, raw_pkg_lines))
+    # Drop blank lines and strip lines from default description
+    pkg_lines = list(filter(None, raw_pkg_lines[:-2]))
 
     pkg_lines_set = set(pkg_lines)
 

setuptools/tests/test_egg_info.py

@@ -875,6 +875,29 @@ def test_long_description_content_type(self, tmpdir_cwd, env):
         assert expected_line in pkg_info_lines
         assert 'Metadata-Version: 2.1' in pkg_info_lines
 
+    def test_long_description(self, tmpdir_cwd, env):
+        # Test that specifying `long_description` and `long_description_content_type`
+        # keyword args to the `setup` function results in writing
+        # the description in the message payload of the `PKG-INFO` file
+        # in the `<distribution>.egg-info` directory.
+        self._setup_script_with_requires(
+            "long_description='This is a long description\\nover multiple lines',"
+            "long_description_content_type='text/markdown',"
+        )
+        code, data = environment.run_setup_py(
+            cmd=['egg_info'],
+            pypath=os.pathsep.join([env.paths['lib'], str(tmpdir_cwd)]),
+            data_stream=1,
+        )
+        egg_info_dir = os.path.join('.', 'foo.egg-info')
+        with open(os.path.join(egg_info_dir, 'PKG-INFO')) as pkginfo_file:
+            pkg_info_lines = pkginfo_file.read().split('\n')
+        assert 'Metadata-Version: 2.1' in pkg_info_lines
+        assert '' == pkg_info_lines[-1]  # last line should be empty
+        long_desc_lines = pkg_info_lines[pkg_info_lines.index(''):]
+        assert 'This is a long description' in long_desc_lines
+        assert 'over multiple lines' in long_desc_lines
+
     def test_project_urls(self, tmpdir_cwd, env):
         # Test that specifying a `project_urls` dict to the `setup`
         # function results in writing multiple `Project-URL` lines to