Mojo: Mojom: Fix NodeList's __eq__ (only used in testing).

mojo/public/tools/bindings/pylib/mojom/parse/ast.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Node objects for the AST for a Mojo IDL file."""
+"""Node classes for the AST for a Mojo IDL file."""
 
 # Note: For convenience of testing, you probably want to define __eq__() methods
 # for all node types; it's okay to be slightly lax (e.g., not compare filename
-# and lineno).
+# and lineno). You may also define __repr__() to help with analyzing test
+# failures, especially for more complex types.
 
 
 class NodeBase(object):
   """Base class for nodes in the AST."""
 
   def __init__(self, filename=None, lineno=None):
     self.filename = filename
     self.lineno = lineno
 
 
+# TODO(vtl): Some of this is complicated enough that it should be tested.
 class NodeListBase(NodeBase):
   """Represents a list of other nodes, all having the same type. (This is meant
   to be subclassed, with subclasses defining _list_item_type to be the class of
   the members of the list; _list_item_type should also be a NodeBase.)"""
 
   def __init__(self, item_or_items=None, **kwargs):
     assert issubclass(self._list_item_type, NodeBase)
     NodeBase.__init__(self, **kwargs)
     if item_or_items is None:
       self.elements = []
     elif isinstance(item_or_items, list):
       # TODO(vtl): Possibly we should assert that each element of the list is a
       # |_list_item_type|.
       self.elements = list(item_or_items)
     else:
       assert isinstance(item_or_items, self._list_item_type)
       self.elements = [item_or_items]
     self._UpdateFilenameAndLineno()
 
   # Support iteration. For everything else, users should just access |elements|
   # directly. (We intentionally do NOT supply |__len__()| or |__nonzero__()|, so
   # |bool(NodeListBase())| is true.)
   def __iter__(self):
     return self.elements.__iter__()
 
   def __eq__(self, other):
-    if type(self) != type(other):
-      return False
-    for element in self.elements:
-      if self.elements != other.elements:
-        return False
-    return True
+    return type(self) == type(other) and \
+           len(self.elements) == len(other.elements) and \
+           all(self.elements[i] == other.elements[i] \
+                   for i in xrange(len(self.elements)))
+
+  # Implement this so that on failure, we get slightly more sensible output.
+  def __repr__(self):
+    return self.__class__.__name__ + "([" + \
+           ", ".join([repr(elem) for elem in self.elements]) + "])"
 
   def Append(self, item):
     assert isinstance(item, self._list_item_type)
     self.elements.append(item)
     self._UpdateFilenameAndLineno()
 
   def _UpdateFilenameAndLineno(self):
     if self.elements:
       self.filename = self.elements[0].filename
       self.lineno = self.elements[0].lineno
@@ skipping 46 matching lines @@
   def __eq__(self, other):
     return self.typename == other.typename and \
            self.name == other.name and \
            self.ordinal == other.ordinal
 
 
 class ParameterList(NodeListBase):
   """Represents a list of (method request or response) parameters."""
 
   _list_item_type = Parameter