code: def test_optimizer(self, backend_config):
      device = backend_config.device
      target = SimpleChain(self.shape)
      target.to_device(device)
      optimizer_cls = getattr(chainer.optimizers, self.optimizer)
      optimizer = optimizer_cls(**self.kwargs)
      optimizer.setup(target)
  
      x_np = np.asarray(np.random.randn(*self.shape)).astype(np.float32)
      x = chainer.Variable(device.send(x_np))
  
      # Just ensures no error occurs. No numerical check is performed.
      optimizer.update(target, x)
  
imports: import pickle
  import unittest
  import numpy
  import six
  import chainer
  from chainer import functions
  from chainer import optimizers
  from chainer import testing
label_desc: Use image node_id 1 for calling the TestOptimizer obj's underlying member method code with example usage: obj.test_optimizer(backend_config) without return types