relative_to_absolute_name will now raise TooManyLevelsError when a relative import is trying to access something beyond the top-level package.

4 files changed, 35 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 55a46022..c064fefe 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,9 @@ Change log for the astroid package (used to be astng)
 =====================================================
 
 --
+    * relative_to_absolute_name or methods calling it will now raise
+      TooManyLevelsError when a relative import was trying to
+      access something beyond the top-level package.     
 
     * AstroidBuildingException is now AstroidBuildingError. The first
       name will exist until astroid 2.0.
diff --git a/astroid/exceptions.py b/astroid/exceptions.py
index 993e4b15..3cfadbd2 100644
--- a/astroid/exceptions.py
+++ b/astroid/exceptions.py
@@ -58,6 +58,21 @@ class AstroidImportError(AstroidBuildingError):
     """Exception class used when a module can't be imported by astroid."""
 
 
+class TooManyLevelsError(AstroidImportError):
+    """Exception class which is raised when a relative import was beyond the top-level.
+
+    Standard attributes:
+        level: The level which was attempted.
+        name: the name of the module on which the relative import was attempted.
+    """
+    level = None
+    name = None
+
+    def __init__(self, message='Relative import with too many levels '
+                               '({level}) for module {name!r}', **kws):
+        super(TooManyLevelsError, self).__init__(message, **kws)
+
+
 class AstroidSyntaxError(AstroidBuildingError):
     """Exception class used when a module can't be parsed."""
 
diff --git a/astroid/scoped_nodes.py b/astroid/scoped_nodes.py
index de4b394e..25d28aed 100644
--- a/astroid/scoped_nodes.py
+++ b/astroid/scoped_nodes.py
@@ -442,6 +442,10 @@ class Module(LocalsDictNodeNG):
         if level:
             if self.package:
                 level = level - 1
+            if level and self.name.count('.') < level:
+                raise exceptions.TooManyLevelsError(
+                    level=level, name=self.name)
+
             package_name = self.name.rsplit('.', level)[0]
         elif self.package:
             package_name = self.name
diff --git a/astroid/tests/unittest_scoped_nodes.py b/astroid/tests/unittest_scoped_nodes.py
index 6f215e47..d49154dc 100644
--- a/astroid/tests/unittest_scoped_nodes.py
+++ b/astroid/tests/unittest_scoped_nodes.py
@@ -32,6 +32,7 @@ from astroid.exceptions import (
     InferenceError, AttributeInferenceError,
     NoDefault, ResolveError, MroError,
     InconsistentMroError, DuplicateBasesError,
+    TooManyLevelsError,
 )
 from astroid.bases import (
     BUILTINS, Instance,
@@ -160,6 +161,18 @@ class ModuleNodeTest(ModuleLoader, unittest.TestCase):
         modname = mod.relative_to_absolute_name('', 1)
         self.assertEqual(modname, 'very.multi')
 
+    def test_relative_to_absolute_name_beyond_top_level(self):
+        mod = nodes.Module('a.b.c', '')
+        mod.package = True
+        for level in (5, 4):
+            with self.assertRaises(TooManyLevelsError) as cm:
+                mod.relative_to_absolute_name('test', level)
+
+            expected = ("Relative import with too many levels "
+                        "({level}) for module {name!r}".format(
+                        level=level - 1, name=mod.name))
+            self.assertEqual(expected, str(cm.exception))
+            
     def test_import_1(self):
         data = '''from . import subpackage'''
         sys.path.insert(0, resources.find('data'))