gclient: Don't allow duplicate entries on deps

Bug: 809671
Change-Id: I74103304651417e6b6889cb713fe494c95279d69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2088422Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>

gclient_eval.py

@@ -26,8 +26,8 @@ else:
 
 class _NodeDict(collections_abc.MutableMapping):
   """Dict-like type that also stores information on AST nodes and tokens."""
-  def __init__(self, data, tokens=None):
-    self.data = collections.OrderedDict(data)
+  def __init__(self, data=None, tokens=None):
+    self.data = collections.OrderedDict(data or [])
     self.tokens = tokens
 
   def __str__(self):
@@ -250,8 +250,15 @@ def _gclient_eval(node_or_string, filename='<unknown>', vars_dict=None):
     elif isinstance(node, ast.List):
       return list(map(_convert, node.elts))
     elif isinstance(node, ast.Dict):
-      return _NodeDict((_convert(k), (_convert(v), v))
-          for k, v in zip(node.keys, node.values))
+      node_dict = _NodeDict()
+      for key_node, value_node in zip(node.keys, node.values):
+        key = _convert(key_node)
+        if key in node_dict:
+          raise ValueError(
+              'duplicate key in dictionary: %s (file %r, line %s)' % (
+                  key, filename, getattr(key_node, 'lineno', '<unknown>')))
+        node_dict.SetNode(key, _convert(value_node), value_node)
+      return node_dict
     elif isinstance(node, ast.Name):
       if node.id not in _allowed_names:
         raise ValueError(

tests/gclient_eval_unittest.py

@@ -173,6 +173,22 @@ class ExecTest(unittest.TestCase):
     self.assertIn('baz was used as a variable, but was not declared',
                   str(cm.exception))
 
+  def test_doesnt_allow_duplicate_deps(self):
+    with self.assertRaises(ValueError) as cm:
+      gclient_eval.Parse('\n'.join([
+        'deps = {',
+        '  "a_dep": {',
+        '    "url": "a_url@a_rev",',
+        '    "condition": "foo",',
+        '  },',
+        '  "a_dep": {',
+        '    "url": "a_url@another_rev",',
+        '    "condition": "not foo",',
+        '  }',
+        '}',
+      ]), '<unknown>')
+    self.assertIn('duplicate key in dictionary: a_dep', str(cm.exception))
+
 
 class UpdateConditionTest(unittest.TestCase):
   def test_both_present(self):
@@ -1052,7 +1068,6 @@ class ParseTest(unittest.TestCase):
     }, local_scope)
 
 
-
 if __name__ == '__main__':
   level = logging.DEBUG if '-v' in sys.argv else logging.FATAL
   logging.basicConfig(