title: Fetch argument <tf.Tensor 'batch:0' shape=(128, 56, 56, 3) dtype=float32> cannot be interpreted as a Tensor.
body: <p>I write a test code,and when I run it ,it said Fetch argument  cannot be interpreted as a Tensor.I really don't know what's going on .Can somebody tell me how to fix it? thank you very much .Here is the code</p>
  
  <pre><code># coding=utf-8
  from  color_1 import read_and_decode, get_batch, get_test_batch
  import color_inference
  import cv2
  import os
  import time
  import numpy as np
  import tensorflow as tf
  import color_train
  import math
  
  EVAL_INTERVAL_SECS=10
  batch_size=128
  num_examples = 10000
  crop_size=56
  def test(test_x, test_y):
      with tf.Graph().as_default() as g:
          image_holder = tf.placeholder(tf.float32, [batch_size, 56, 56, 3], name='x-input')
          label_holder = tf.placeholder(tf.int32, [batch_size], name='y-input')
  
          y=color_inference.inference(image_holder)
  
          num_iter = int(math.ceil(num_examples / batch_size))
          true_count = 0
          total_sample_count = num_iter * batch_size
          saver=tf.train.Saver()
          top_k_op = tf.nn.in_top_k(y, label_holder, 1)
          while True:
              with tf.Session() as sess:
                  ckpt=tf.train.get_checkpoint_state(color_train.MODEL_SAVE_PATH)
                  if ckpt and ckpt.model_checkpoint_path:
                      saver.restore(sess,ckpt.model_checkpoint_path)
                      global_step=ckpt.model_checkpoint_path.split('/')[-1].split('-')[-1]
                      image_batch, label_batch = sess.run([test_x, test_y])
                      predictions = sess.run([top_k_op], feed_dict={image_holder: image_batch,
                                                                    label_holder: label_batch})
                      true_count += np.sum(predictions)
                      precision = true_count * 1.0 / total_sample_count
                      print("After %s training step,the prediction is :%g",global_step,precision)
                  else:
                      print('No checkpoint file found')
                      return
              time.sleep(EVAL_INTERVAL_SECS)
  
  def main(argv=None):
      test_image, test_label = read_and_decode('val.tfrecords')
      test_images, test_labels = get_test_batch(test_image, test_label, batch_size, crop_size)
      test(test_images, test_labels)
  
  if __name__=='__main__':
      tf.app.run()
  </code></pre>
  
  <p>And the error is here:</p>
  
  <pre><code>File "/home/vrview/tensorflow/example/char/tfrecords/color_test.py", line 57, in &lt;module&gt;
      tf.app.run()
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/platform/app.py", line 44, in run
      _sys.exit(main(_sys.argv[:1] + flags_passthrough))
    File "/home/vrview/tensorflow/example/char/tfrecords/color_test.py", line 54, in main
      test(test_images, test_labels)
    File "/home/vrview/tensorflow/example/char/tfrecords/color_test.py", line 39, in test
      image_batch, label_batch = sess.run([test_x, test_y])
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 767, in run
      run_metadata_ptr)
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 952, in _run
      fetch_handler = _FetchHandler(self._graph, fetches, feed_dict_string)
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 408, in __init__
      self._fetch_mapper = _FetchMapper.for_fetch(fetches)
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 230, in for_fetch
      return _ListFetchMapper(fetch)
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 337, in __init__
      self._mappers = [_FetchMapper.for_fetch(fetch) for fetch in fetches]
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 238, in for_fetch
      return _ElementFetchMapper(fetches, contraction_fn)
    File "/home/vrview/tensorflow/local/lib/python2.7/site-packages/tensorflow/python/client/session.py", line 274, in __init__
      'Tensor. (%s)' % (fetch, str(e)))
  ValueError: Fetch argument &lt;tf.Tensor 'batch:0' shape=(128, 56, 56, 3) dtype=float32&gt; cannot be interpreted as a Tensor. (Tensor Tensor("batch:0", shape=(128, 56, 56, 3), dtype=float32) is not an element of this graph.)
  </code></pre>