fix: fallback to importlib_metadata when loading entry points

since `pkg_resources` is deprecated for this purpose, per
https://setuptools.pypa.io/en/latest/pkg_resources.html

src/wuttjamaican/util.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  WuttJamaican -- Base package for Wutta Framework
-#  Copyright © 2023 Lance Edgar
+#  Copyright © 2023-2024 Lance Edgar
 #
 #  This file is part of Wutta Framework.
 #
@@ -58,44 +58,27 @@ def load_entry_points(group, ignore_errors=False):
 
     try:
         # nb. this package was added in python 3.8
-        import importlib.metadata
+        import importlib.metadata as importlib_metadata
-
     except ImportError:
-        # older setup, must use pkg_resources
+        import importlib_metadata
-        # TODO: remove this section once we require python 3.8
-        from pkg_resources import iter_entry_points
-
-        for entry_point in iter_entry_points(group):
-            try:
-                ep = entry_point.load()
-            except:
-                if not ignore_errors:
-                    raise
-                log.warning("failed to load entry point: %s", entry_point,
-                            exc_info=True)
-            else:
-                entry_points[entry_point.name] = ep
 
+    eps = importlib_metadata.entry_points()
+    if not hasattr(eps, 'select'):
+        # python < 3.10
+        eps = eps.get(group, [])
     else:
-        # newer setup (python >= 3.8); can use importlib, but the
+        # python >= 3.10
-        # details may vary
+        eps = eps.select(group=group)
-        eps = importlib.metadata.entry_points()
+    for entry_point in eps:
-        if not hasattr(eps, 'select'):
+        try:
-            # python < 3.10
+            ep = entry_point.load()
-            eps = eps.get(group, [])
+        except:
+            if not ignore_errors:
+                raise
+            log.warning("failed to load entry point: %s", entry_point,
+                        exc_info=True)
         else:
-            # python >= 3.10
+            entry_points[entry_point.name] = ep
-            eps = eps.select(group=group)
-        for entry_point in eps:
-            try:
-                ep = entry_point.load()
-            except:
-                if not ignore_errors:
-                    raise
-                log.warning("failed to load entry point: %s", entry_point,
-                            exc_info=True)
-            else:
-                entry_points[entry_point.name] = ep
 
     return entry_points
 

tests/test_util.py

@@ -51,7 +51,44 @@ class TestLoadEntryPoints(TestCase):
             # even in a testing environment.  basic sanity check
             result = util.load_entry_points('console_scripts', ignore_errors=True)
             self.assertTrue(len(result) >= 1)
-            self.assertIn('pip', result)
+            self.assertIn('pytest', result)
+
+    def test_basic_pre_python_3_8(self):
+
+        # the goal here is to get coverage for code which would only
+        # run on python 3.7 and older, but we only need that coverage
+        # if we are currently testing python 3.8+
+        if sys.version_info.major == 3 and sys.version_info.minor < 8:
+            pytest.skip("this test is not relevant before python 3.8")
+
+        from importlib.metadata import entry_points
+        real_entry_points = entry_points()
+
+        class FakeEntryPoints(dict):
+            def get(self, group, default):
+                if hasattr(real_entry_points, 'select'):
+                    return real_entry_points.select(group=group)
+                return real_entry_points.get(group, [])
+
+        importlib_metadata = MagicMock()
+        importlib_metadata.entry_points.return_value = FakeEntryPoints()
+
+        orig_import = __import__
+
+        def mock_import(name, *args, **kwargs):
+            if name == 'importlib.metadata':
+                raise ImportError
+            if name == 'importlib_metadata':
+                return importlib_metadata
+            return orig_import(name, *args, **kwargs)
+
+        with patch('builtins.__import__', side_effect=mock_import):
+
+            # load some entry points which should "always" be present,
+            # even in a testing environment.  basic sanity check
+            result = util.load_entry_points('console_scripts', ignore_errors=True)
+            self.assertTrue(len(result) >= 1)
+            self.assertIn('pytest', result)
 
     def test_error(self):
 
@@ -86,66 +123,6 @@ class TestLoadEntryPoints(TestCase):
             entry_points.select.assert_called_once_with(group='wuttatest.thingers')
             entry_point.load.assert_called_once_with()
 
-    def test_pkg_resources_empty(self):
-        orig_import = __import__
-
-        def mock_import(name, *args, **kwargs):
-            if name == 'importlib.metadata':
-                raise ImportError
-            return orig_import(name, *args, **kwargs)
-
-        with patch('builtins.__import__', side_effect=mock_import):
-
-            # empty set returned for unknown group
-            result = util.load_entry_points('this_should_never_exist!!!!!!')
-            self.assertEqual(result, {})
-
-    def test_pkg_resources_basic(self):
-        orig_import = __import__
-
-        def mock_import(name, *args, **kwargs):
-            if name == 'importlib.metadata':
-                raise ImportError
-            return orig_import(name, *args, **kwargs)
-
-        with patch('builtins.__import__', side_effect=mock_import):
-
-            # load some entry points which should "always" be present,
-            # even in a testing environment.  basic sanity check
-            result = util.load_entry_points('console_scripts', ignore_errors=True)
-            self.assertTrue(len(result) >= 1)
-            self.assertIn('pip', result)
-
-    def test_pkg_resources_error(self):
-        orig_import = __import__
-
-        entry_point = MagicMock()
-        entry_point.load.side_effect = NotImplementedError
-
-        iter_entry_points = MagicMock(return_value=[entry_point])
-        pkg_resources = MagicMock(iter_entry_points=iter_entry_points)
-
-        def mock_import(name, *args, **kwargs):
-            if name == 'importlib.metadata':
-                raise ImportError
-            return orig_import(name, *args, **kwargs)
-
-        with patch('builtins.__import__', side_effect=mock_import):
-            with patch.dict('sys.modules', **{'pkg_resources': pkg_resources}):
-
-                # empty set returned if errors suppressed
-                result = util.load_entry_points('wuttatest.thingers', ignore_errors=True)
-                self.assertEqual(result, {})
-                iter_entry_points.assert_called_once_with('wuttatest.thingers')
-                entry_point.load.assert_called_once_with()
-
-                # error is raised, if not suppressed
-                iter_entry_points.reset_mock()
-                entry_point.load.reset_mock()
-                self.assertRaises(NotImplementedError, util.load_entry_points, 'wuttatest.thingers')
-                iter_entry_points.assert_called_once_with('wuttatest.thingers')
-                entry_point.load.assert_called_once_with()
-
 
 class TestLoadObject(TestCase):