Some nodes got a new attribute, 'ctx', which tells in which context the said node was used.

The possible values for the contexts are `Load` ('a'), `Del` ('del a'),
`Store` ('a = 4') and the nodes that got the new attribute are Starred,
Subscript, List and Tuple. The builtin ast module provides contexts for
Name and Attribute as well, but we took a different approach in the past,
by having different nodes for each type of context. For instance, Name
used in a Del context is a DelName, while Name used in a Store
context is AssignName. Since this is ingrained in astroid since quite
some time, it makes no sense to change them as well, even though it's
a loss of consistency.
The patch introduces a new dependency to enum34 on older Python
versions, which is used for building the three possible enum values
for the contexts.

Closes issue #267.

1 files changed, 50 insertions, 0 deletions

diff --git a/astroid/tests/unittest_nodes.py b/astroid/tests/unittest_nodes.py
index 8abd85e..cf32ce9 100644
--- a/astroid/tests/unittest_nodes.py
+++ b/astroid/tests/unittest_nodes.py
@@ -25,6 +25,7 @@ import warnings
 
 import six
 
+import astroid
 from astroid import bases
 from astroid import builder
 from astroid import context as contextmod
@@ -757,5 +758,54 @@ class Python35AsyncTest(unittest.TestCase):
         self._test_await_async_as_string(code)
 
 
+class ContextTest(unittest.TestCase):
+
+    def test_subscript_load(self):
+        node = test_utils.extract_node('f[1]')
+        self.assertIs(node.ctx, astroid.Load)
+
+    def test_subscript_del(self):
+        node = test_utils.extract_node('del f[1]')
+        self.assertIs(node.targets[0].ctx, astroid.Del)
+
+    def test_subscript_store(self):
+        node = test_utils.extract_node('f[1] = 2')
+        subscript = node.targets[0]
+        self.assertIs(subscript.ctx, astroid.Store)
+
+    def test_list_load(self):
+        node = test_utils.extract_node('[]')
+        self.assertIs(node.ctx, astroid.Load)
+
+    def test_list_del(self):
+        node = test_utils.extract_node('del []')
+        self.assertIs(node.targets[0].ctx, astroid.Del)
+
+    def test_list_store(self):
+        with self.assertRaises(exceptions.AstroidSyntaxError):
+            test_utils.extract_node('[0] = 2')
+
+    def test_tuple_load(self):
+        node = test_utils.extract_node('(1, )')
+        self.assertIs(node.ctx, astroid.Load)
+
+    def test_tuple_store(self):
+        with self.assertRaises(exceptions.AstroidSyntaxError):
+            test_utils.extract_node('(1, ) = 3')
+
+    @test_utils.require_version(minver='3.5')
+    def test_starred_load(self):
+        node = test_utils.extract_node('a = *b')
+        starred = node.value
+        self.assertIs(starred.ctx, astroid.Load)
+
+    @test_utils.require_version(minver='3.0')
+    def test_starred_store(self):
+        node = test_utils.extract_node('a, *b = 1, 2')
+        starred = node.targets[0].elts[1]
+        self.assertIs(starred.ctx, astroid.Store) 
+        
+        
+
 if __name__ == '__main__':
     unittest.main()