message: Update outside compilation failure test to make use of string tensors
  Without usage of the string tensor, it can be pruned and doesn't produce the error with MLIR bridge phase 1.
diff: @@ -295,8 +295,8 @@ class TPUStrategyTest(test.TestCase, parameterized.TestCase):
  def train_fn(iterator):
  def step_fn(inputs):
  - _, inputs = inputs
  - return math_ops.reduce_sum(inputs)
  + input0, input1 = inputs
  + return array_ops.size(input0), math_ops.reduce_sum(input1)
  return strategy.experimental_local_results(
  strategy.run(step_fn, args=(next(iterator),)))
  