Module.__path__ is now a list

It used to be a string containing the path, but it doesn't reflect the situation
on Python, where it is actually a list.
Also fix a bug with namespace package's __path__ attribute, which wasn't using the
module's __path__, but its file attribute, which is None for namespace packages.

Close #528

4 files changed, 25 insertions, 6 deletions

diff --git a/ChangeLog b/ChangeLog
index de01f065..f828242b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,16 @@ Change log for the astroid package (used to be astng)
 =====================================================
 
 --
+
+   * Module.__path__ is now a list
+
+     It used to be a string containing the path, but it doesn't reflect the situation
+     on Python, where it is actually a list.
+
+   * Fix a bug with namespace package's __path__ attribute.
+
+     Close #528
+
    * Added brain tips for random.sample
 
      Part of PyCQA/pylint#811
diff --git a/astroid/interpreter/objectmodel.py b/astroid/interpreter/objectmodel.py
index 096a8939..bae60fc5 100644
--- a/astroid/interpreter/objectmodel.py
+++ b/astroid/interpreter/objectmodel.py
@@ -127,11 +127,16 @@ class ModuleModel(ObjectModel):
             raise exceptions.AttributeInferenceError(target=self._instance,
                                                      attribute='__path__')
 
-        path = os.path.dirname(self._instance.file)
-        path_obj = node_classes.Const(value=path, parent=self._instance)
+        path_objs = [
+            node_classes.Const(
+                value=path if not path.endswith('__init__.py') else os.path.dirname(path),
+                parent=self._instance
+            )
+            for path in self._instance.path
+        ]
 
         container = node_classes.List(parent=self._instance)
-        container.postinit([path_obj])
+        container.postinit(path_objs)
 
         return container
 
diff --git a/astroid/rebuilder.py b/astroid/rebuilder.py
index a323e972..5d4ffcff 100644
--- a/astroid/rebuilder.py
+++ b/astroid/rebuilder.py
@@ -125,7 +125,8 @@ class TreeRebuilder(object):
     def visit_module(self, node, modname, modpath, package):
         """visit a Module node by returning a fresh instance of it"""
         node, doc = _get_doc(node)
-        newnode = nodes.Module(name=modname, doc=doc, file=modpath, path=modpath,
+        newnode = nodes.Module(name=modname, doc=doc, file=modpath,
+                               path=[modpath],
                                package=package, parent=None)
         newnode.postinit([self.visit(child, newnode) for child in node.body])
         return newnode
diff --git a/astroid/scoped_nodes.py b/astroid/scoped_nodes.py
index c0d75b5a..7d313605 100644
--- a/astroid/scoped_nodes.py
+++ b/astroid/scoped_nodes.py
@@ -19,6 +19,7 @@ import sys
 import io
 import itertools
 import warnings
+from typing import Optional, List
 
 from astroid import bases
 from astroid import context as contextmod
@@ -354,7 +355,9 @@ class Module(LocalsDictNodeNG):
                      'pure_python', 'future_imports')
     _other_other_fields = ('locals', 'globals')
 
-    def __init__(self, name, doc, file=None, path=None, package=None,
+    def __init__(self, name, doc, file=None,
+                 path: Optional[List[str]]=None,
+                 package=None,
                  parent=None, pure_python=True):
         """
         :param name: The name of the module.
@@ -367,7 +370,7 @@ class Module(LocalsDictNodeNG):
         :type file: str or None
 
         :param path:
-        :type path: str or None
+        :type path: Optional[List[str]]
 
         :param package: Whether the node represents a package or a module.
         :type package: bool or None