'If a L{FlattenerError} is created with an L{IRenderable} provider root,
the repr of that object is included in the string representation of the
exception.'

def test_renderable(self):

    @implementer(IRenderable)
    class Renderable(object, ):
        def __repr__(self):
            return 'renderable    repr'
    self.assertEqual(str(FlattenerError(RuntimeError('reason'), [Renderable()], [])), 'Exception    while    flattening:\n        renderable    repr\nRuntimeError:    reason\n')
