message: Add a few tests for more complex cases of error handling.
diff: @@ -164,6 +164,9 @@ class DirectivesTransformer(converter.Base):
  self.state[_LoopScope].enter()
  self.state[_LoopScope].ast_node = node
  node = self.generic_visit(node)
  + # Edge case: a loop with just one directive statement would become empty.
  + if not node.body:
  + node.body = [gast.Pass()]
  self.state[_LoopScope].exit()
  return node
  