Added a new error, 'relative-beyond-top-level'.

This is emitted when a relative import was attempted beyond the top level package.
For instance, if a package has X levels, trying to climb X + n levels with a relative
import, as in `from ..stuff import Stuff`, will result in an error.
Closes issue #588.

5 files changed, 57 insertions, 10 deletions

diff --git a/ChangeLog b/ChangeLog
index 082c558..c9410a9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,10 +2,16 @@ ChangeLog for Pylint
 --------------------
 
 --
-     * Accept only functions and methods for the deprecated-method checker.
+    
+    * Added a new error, 'relative-beyond-top-level', which is emitted
+      when a relative import was attempted beyond the top level package.
 
-      This prevents a crash which can occur when an object doesn't have
-      .qname() method after the inference.
+      Closes issue #588.
+
+    * Accept only functions and methods for the deprecated-method checker.
+
+     This prevents a crash which can occur when an object doesn't have
+     .qname() method after the inference.
 
     * Don't emit super-on-old-class on classes with unknown bases.
       Closes issue #721.
diff --git a/pylint/checkers/imports.py b/pylint/checkers/imports.py
index 5863130..2fdcc85 100644
--- a/pylint/checkers/imports.py
+++ b/pylint/checkers/imports.py
@@ -88,6 +88,14 @@ def _get_first_import(node, context, name, base, level):
     if found and not are_exclusive(first, node):
         return first
 
+
+def _ignore_import_failure(node, modname, ignored_modules):
+    for submodule in _qualified_names(modname):
+        if submodule in ignored_modules:
+            return True
+
+    return node_ignores_exception(node, ImportError)
+
 # utilities to represents import dependencies as tree and dot graph ###########
 
 def _make_tree_defs(mod_files_list):
@@ -161,6 +169,10 @@ MSGS = {
               'import-error',
               'Used when pylint has been unable to import a module.',
               {'old_names': [('F0401', 'import-error')]}),
+    'E0402': ('Attempted relative import beyond top-level package',
+              'relative-beyond-top-level',
+              'Used when a relative import tries to access too many levels '
+              'in the current package.'),
     'R0401': ('Cyclic import (%s)',
               'cyclic-import',
               'Used when a cyclic import between two or more modules is \
@@ -461,16 +473,18 @@ given file (report RP0402 must not be disabled)'}
     def _get_imported_module(self, importnode, modname):
         try:
             return importnode.do_import_module(modname)
-        except astroid.AstroidBuildingException as exc:
-            for submodule in _qualified_names(modname):
-                if submodule in self._ignored_modules:
-                    return None
+        except astroid.TooManyLevelsError:
+            if _ignore_import_failure(importnode, modname, self._ignored_modules):
+                return None
+
+            self.add_message('relative-beyond-top-level', node=importnode)            
 
-            if node_ignores_exception(importnode, ImportError):
+        except astroid.AstroidBuildingException as exc:
+            if _ignore_import_failure(importnode, modname, self._ignored_modules):
                 return None
 
             dotted_modname = _get_import_name(importnode, modname)
-            self.add_message("import-error", args=repr(dotted_modname),
+            self.add_message('import-error', args=repr(dotted_modname),
                              node=importnode)
 
     def _check_relative_import(self, modnode, importnode, importedmodnode,
diff --git a/pylint/test/regrtest_data/beyond_top/__init__.py b/pylint/test/regrtest_data/beyond_top/__init__.py
new file mode 100644
index 0000000..401fe06
--- /dev/null
+++ b/pylint/test/regrtest_data/beyond_top/__init__.py
@@ -0,0 +1,6 @@
+from ... import Something

+from . import data

+try:

+    from ... import Lala

+except ImportError:

+    pass
\ No newline at end of file
diff --git a/pylint/test/regrtest_data/beyond_top/data.py b/pylint/test/regrtest_data/beyond_top/data.py
new file mode 100644
index 0000000..9ec64d2
--- /dev/null
+++ b/pylint/test/regrtest_data/beyond_top/data.py
@@ -0,0 +1 @@
+Anything = 42
\ No newline at end of file
diff --git a/pylint/test/unittest_checker_imports.py b/pylint/test/unittest_checker_imports.py
index f5e6bbb..0069be2 100644
--- a/pylint/test/unittest_checker_imports.py
+++ b/pylint/test/unittest_checker_imports.py
@@ -1,6 +1,8 @@
 """Unit tests for the imports checker."""
+import os
 import unittest
 
+import astroid
 from astroid import test_utils
 from pylint.checkers import imports
 from pylint.testutils import CheckerTestCase, Message, set_config
@@ -62,7 +64,7 @@ class ImportsCheckerTC(CheckerTestCase):
         with self.assertNoMessages():
             self.checker.visit_import(node)
 
-    def test_visit_importfrom(self):
+    def test_reimported_same_line(self):
         """
         Test that duplicate imports on single line raise 'reimported'.
         """
@@ -71,5 +73,23 @@ class ImportsCheckerTC(CheckerTestCase):
         with self.assertAddsMessages(msg):
             self.checker.visit_importfrom(node)
 
+    def test_relative_beyond_top_level(self):
+        here = os.path.abspath(os.path.dirname(__file__))
+        path = os.path.join(here, 'regrtest_data', 'beyond_top', '__init__.py')
+        with open(path) as stream:
+            data = stream.read()
+        module = astroid.parse(data, module_name='beyond_top', path=path)
+        import_from = module.body[0]
+
+        msg = Message(msg_id='relative-beyond-top-level',
+                      node=import_from)
+        with self.assertAddsMessages(msg):
+            self.checker.visit_importfrom(import_from)    
+        with self.assertNoMessages():
+            self.checker.visit_importfrom(module.body[1])
+        with self.assertNoMessages():
+            self.checker.visit_importfrom(module.body[2].body[0])
+
+
 if __name__ == '__main__':
     unittest.main()