Defer EntryPoint value validation until loading

importlib_metadata/__init__.py

@@ -179,9 +179,11 @@ class EntryPoint:
     ...
     ValueError: ('Invalid object reference...invalid-name...
 
-    The same thing happens on construction.
+    Construction never raises; the value is validated only when
+    accessed or loaded.
 
-    >>> EntryPoint(name=None, group=None, value='invalid-name')
+    >>> ep = EntryPoint(name=None, group=None, value='invalid-name')
+    >>> ep.load()
     Traceback (most recent call last):
     ...
     ValueError: ('Invalid object reference...invalid-name...
@@ -217,8 +219,6 @@ class EntryPoint:
 
     def __init__(self, name: str, value: str, group: str) -> None:
         vars(self).update(name=name, value=value, group=group)
-        # resolve the value now, raising ValueError if it's invalid
-        _ = self.module
 
     def load(self) -> Any:
         """Load the entry point from its definition. If only a module

newsfragments/523.bugfix.rst

@@ -0,0 +1,4 @@
+Restored lazy validation of ``EntryPoint.value``, deferring the ``ValueError``
+for an invalid value until a component is accessed or the entry point is
+loaded, so one malformed entry point no longer prevents entry points in other
+groups from being selected.

tests/test_api.py

@@ -132,6 +132,36 @@ def test_entry_points_missing_name(self):
     def test_entry_points_missing_group(self):
         assert entry_points(group='missing') == ()
 
+    def test_entry_points_invalid_value_in_other_group(self):
+        """
+        An invalid value in one group should not prevent entry points
+        in other groups from being selected.
+        """
+        alt_site_dir = self.fixtures.enter_context(fixtures.tmp_path())
+        self.fixtures.enter_context(self.add_sys_path(alt_site_dir))
+        alt_pkg = {
+            "invalid_entry_points-1.0.0.dist-info": {
+                "METADATA": """
+                Name: invalid-entry-points
+                Version: 1.0.0
+                """,
+                "entry_points.txt": """
+                [selected]
+                valid = mod:main
+
+                [unselected]
+                invalid = invalid-name
+            """,
+            },
+        }
+        fixtures.build_files(alt_pkg, alt_site_dir)
+
+        assert [ep.name for ep in entry_points(group='selected')] == ['valid']
+
+        # the invalid value is still rejected when the entry point is used
+        with self.assertRaises(ValueError):
+            entry_points(group='unselected')['invalid'].load()
+
     def test_entry_points_allows_no_attributes(self):
         ep = entry_points().select(group='entries', name='main')
         with self.assertRaises(AttributeError):