bpo-37444: Update differing exception between builtins and importlib

Author: nsiregar

Lib/importlib/_bootstrap.py

@@ -873,7 +873,7 @@ def _resolve_name(name, package, level):
     """Resolve a relative module name to an absolute one."""
     bits = package.rsplit('.', level - 1)
     if len(bits) < level:
-        raise ValueError('attempted relative import beyond top-level package')
+        raise ImportError('attempted relative import beyond top-level package')
     base = bits[0]
     return '{}.{}'.format(base, name) if name else base
 

Lib/importlib/util.py

@@ -29,8 +29,8 @@ def resolve_name(name, package):
     if not name.startswith('.'):
         return name
     elif not package:
-        raise ValueError(f'no package specified for {repr(name)} '
-                         '(required for relative module names)')
+        raise ImportError(f'no package specified for {repr(name)} '
+                          '(required for relative module names)')
     level = 0
     for character in name:
         if character != '.':

Lib/test/test_importlib/import_/test_relative_imports.py

@@ -156,7 +156,7 @@ def test_too_high_from_package(self):
                     {'__name__': 'pkg', '__path__': ['blah']})
         def callback(global_):
             self.__import__('pkg')
-            with self.assertRaises(ValueError):
+            with self.assertRaises(ImportError):
                 self.__import__('', global_, fromlist=['top_level'],
                                     level=2)
         self.relative_import_test(create, globals_, callback)
@@ -167,7 +167,7 @@ def test_too_high_from_module(self):
         globals_ = {'__package__': 'pkg'}, {'__name__': 'pkg.module'}
         def callback(global_):
             self.__import__('pkg')
-            with self.assertRaises(ValueError):
+            with self.assertRaises(ImportError):
                 self.__import__('', global_, fromlist=['top_level'],
                                     level=2)
         self.relative_import_test(create, globals_, callback)

Lib/test/test_importlib/test_util.py

@@ -375,7 +375,7 @@ def test_absolute_within_package(self):
 
     def test_no_package(self):
         # .bacon in ''
-        with self.assertRaises(ValueError):
+        with self.assertRaises(ImportError):
             self.util.resolve_name('.bacon', '')
 
     def test_in_package(self):
@@ -390,7 +390,7 @@ def test_other_package(self):
 
     def test_escape(self):
         # ..bacon in spam
-        with self.assertRaises(ValueError):
+        with self.assertRaises(ImportError):
             self.util.resolve_name('..bacon', 'spam')
 
 
@@ -518,7 +518,7 @@ def test_find_relative_module_missing_package(self):
         with util.temp_module(name, pkg=True) as pkg_dir:
             fullname, _ = util.submodule(name, subname, pkg_dir)
             relname = '.' + subname
-            with self.assertRaises(ValueError):
+            with self.assertRaises(ImportError):
                 self.util.find_spec(relname)
             self.assertNotIn(name, sorted(sys.modules))
             self.assertNotIn(fullname, sorted(sys.modules))

Misc/NEWS.d/next/Core and Builtins/2019-07-20-22-34-42.bpo-37444.UOd3Xs.rst

@@ -0,0 +1 @@
+Update differing exception between buildints and importlib

Python/import.c

@@ -1671,7 +1671,7 @@ resolve_name(PyThreadState *tstate, PyObject *name, PyObject *globals, int level
             goto error;
         }
         else if (last_dot == -1) {
-            _PyErr_SetString(tstate, PyExc_ValueError,
+            _PyErr_SetString(tstate, PyExc_ImportError,
                              "attempted relative import beyond top-level "
                              "package");
             goto error;