Handle empty modname in ast_from_module_name (#1801)

astroid/manager.py

@@ -165,6 +165,8 @@ def ast_from_module_name(  # noqa: C901
         use_cache: bool = True,
     ) -> nodes.Module:
         """Given a module name, return the astroid object."""
+        if modname is None:
+            raise AstroidBuildingError("No module name given.")
         # Sometimes we don't want to use the cache. For example, when we're
         # importing a module with the same name as the file that is importing
         # we want to fallback on the import system to make sure we get the correct

tests/unittest_manager.py

@@ -365,6 +365,10 @@ def test_same_name_import_module(self) -> None:
         stdlib_math = next(module.body[1].value.args[0].infer())
         assert self.manager.astroid_cache["math"] != stdlib_math
 
+    def test_raises_exception_for_empty_modname(self) -> None:
+        with pytest.raises(AstroidBuildingError):
+            self.manager.ast_from_module_name(None)
+
 
 class BorgAstroidManagerTC(unittest.TestCase):
     def test_borg(self) -> None: