bpo-43926: Cleaner metadata with PEP 566 JSON support. (GH-25565)

* bpo-43926: Cleaner metadata with PEP 566 JSON support.

* Add blurb

* Add versionchanged and versionadded declarations for changes to metadata.

* Use descriptor for PEP 566

3 files changed, 37 insertions, 3 deletions

diff --git a/Lib/test/test_importlib/fixtures.py b/Lib/test/test_importlib/fixtures.py
index 1ae70c7..12ed07d 100644
--- a/Lib/test/test_importlib/fixtures.py
+++ b/Lib/test/test_importlib/fixtures.py
@@ -1,5 +1,6 @@
 import os
 import sys
+import copy
 import shutil
 import pathlib
 import tempfile
@@ -108,6 +109,16 @@ class DistInfoPkg(OnSysPath, SiteDir):
         super(DistInfoPkg, self).setUp()
         build_files(DistInfoPkg.files, self.site_dir)
 
+    def make_uppercase(self):
+        """
+        Rewrite metadata with everything uppercase.
+        """
+        shutil.rmtree(self.site_dir / "distinfo_pkg-1.0.0.dist-info")
+        files = copy.deepcopy(DistInfoPkg.files)
+        info = files["distinfo_pkg-1.0.0.dist-info"]
+        info["METADATA"] = info["METADATA"].upper()
+        build_files(files, self.site_dir)
+
 
 class DistInfoPkgWithDot(OnSysPath, SiteDir):
     files: FilesDef = {
diff --git a/Lib/test/test_importlib/test_main.py b/Lib/test/test_importlib/test_main.py
index 08069c9..52cb637 100644
--- a/Lib/test/test_importlib/test_main.py
+++ b/Lib/test/test_importlib/test_main.py
@@ -125,7 +125,7 @@ class NonASCIITests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
         metadata_dir.mkdir()
         metadata = metadata_dir / 'METADATA'
         with metadata.open('w', encoding='utf-8') as fp:
-            fp.write('Description: pôrˈtend\n')
+            fp.write('Description: pôrˈtend')
         return 'portend'
 
     @staticmethod
@@ -145,7 +145,7 @@ class NonASCIITests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
 
                 pôrˈtend
                 """
-                ).lstrip()
+                ).strip()
             )
         return 'portend'
 
@@ -157,7 +157,7 @@ class NonASCIITests(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
     def test_metadata_loads_egg_info(self):
         pkg_name = self.pkg_with_non_ascii_description_egg_info(self.site_dir)
         meta = metadata(pkg_name)
-        assert meta.get_payload() == 'pôrˈtend\n'
+        assert meta['Description'] == 'pôrˈtend'
 
 
 class DiscoveryTests(fixtures.EggInfoPkg, fixtures.DistInfoPkg, unittest.TestCase):
diff --git a/Lib/test/test_importlib/test_metadata_api.py b/Lib/test/test_importlib/test_metadata_api.py
index 657c166..825edc1 100644
--- a/Lib/test/test_importlib/test_metadata_api.py
+++ b/Lib/test/test_importlib/test_metadata_api.py
@@ -231,6 +231,29 @@ class APITests(
 
         assert deps == expected
 
+    def test_as_json(self):
+        md = metadata('distinfo-pkg').json
+        assert 'name' in md
+        assert md['keywords'] == ['sample', 'package']
+        desc = md['description']
+        assert desc.startswith('Once upon a time\nThere was')
+        assert len(md['requires_dist']) == 2
+
+    def test_as_json_egg_info(self):
+        md = metadata('egginfo-pkg').json
+        assert 'name' in md
+        assert md['keywords'] == ['sample', 'package']
+        desc = md['description']
+        assert desc.startswith('Once upon a time\nThere was')
+        assert len(md['classifier']) == 2
+
+    def test_as_json_odd_case(self):
+        self.make_uppercase()
+        md = metadata('distinfo-pkg').json
+        assert 'name' in md
+        assert len(md['requires_dist']) == 2
+        assert md['keywords'] == ['SAMPLE', 'PACKAGE']
+
 
 class LegacyDots(fixtures.DistInfoPkgWithDotLegacy, unittest.TestCase):
     def test_name_normalization(self):