bpo-34632: Add importlib.metadata (GH-12547)

Add importlib.metadata module as forward port of the standalone importlib_metadata.

Lib/test/test_importlib/test_zip.py

@@ -0,0 +1,56 @@
+import sys
+import unittest
+
+from contextlib import ExitStack
+from importlib.metadata import distribution, entry_points, files, version
+from importlib.resources import path
+
+
+class TestZip(unittest.TestCase):
+    root = 'test.test_importlib.data'
+
+    def setUp(self):
+        # Find the path to the example-*.whl so we can add it to the front of
+        # sys.path, where we'll then try to find the metadata thereof.
+        self.resources = ExitStack()
+        self.addCleanup(self.resources.close)
+        wheel = self.resources.enter_context(
+            path(self.root, 'example-21.12-py3-none-any.whl'))
+        sys.path.insert(0, str(wheel))
+        self.resources.callback(sys.path.pop, 0)
+
+    def test_zip_version(self):
+        self.assertEqual(version('example'), '21.12')
+
+    def test_zip_entry_points(self):
+        scripts = dict(entry_points()['console_scripts'])
+        entry_point = scripts['example']
+        self.assertEqual(entry_point.value, 'example:main')
+
+    def test_missing_metadata(self):
+        self.assertIsNone(distribution('example').read_text('does not exist'))
+
+    def test_case_insensitive(self):
+        self.assertEqual(version('Example'), '21.12')
+
+    def test_files(self):
+        for file in files('example'):
+            path = str(file.dist.locate_file(file))
+            assert '.whl/' in path, path
+
+
+class TestEgg(TestZip):
+    def setUp(self):
+        # Find the path to the example-*.egg so we can add it to the front of
+        # sys.path, where we'll then try to find the metadata thereof.
+        self.resources = ExitStack()
+        self.addCleanup(self.resources.close)
+        egg = self.resources.enter_context(
+            path(self.root, 'example-21.12-py3.6.egg'))
+        sys.path.insert(0, str(egg))
+        self.resources.callback(sys.path.pop, 0)
+
+    def test_files(self):
+        for file in files('example'):
+            path = str(file.dist.locate_file(file))
+            assert '.egg/' in path, path