EXPECT_EQ(op_def.input_arg_size(), 0);
  EXPECT_EQ(op_def.output_arg_size(), 1);
  EXPECT_TRUE(op_def.is_stateful());

  TF_DeleteBuffer(buffer);
}

void AssertEqual(TF_Function* f1, TF_Function* f2) {
  string s1, s2;
  tensorflow::FunctionDef fdef1, fdef2;
  ASSERT_TRUE(GetFunctionDef(f1, &fdef1));
  ASSERT_TRUE(GetFunctionDef(f2, &fdef2));
  SerializeToStringDeterministic(fdef1, &s1);

      found_scalar_const = true;
    } else if (IsAddN(n, 2)) {
      EXPECT_FALSE(found_add);
      found_add = true;
    } else {
      ADD_FAILURE() << "Unexpected NodeDef: " << n.DebugString();
    }
  }
  EXPECT_TRUE(found_placeholder);
  EXPECT_TRUE(found_scalar_const);
  EXPECT_TRUE(found_add);

  // Add another oper to the graph.
  TF_Operation* neg = Neg(add, graph, s);

    ASSERT_TRUE(TF_GetCode(status) == TF_OK) << TF_Message(status);
    const char* device_name = TFE_OpGetDevice(matmul, status);
    ASSERT_TRUE(strstr(device_name, "GPU:0") != nullptr);

    TFE_OpSetDevice(matmul, "CPU:0", status);
    ASSERT_TRUE(TF_GetCode(status) == TF_OK) << TF_Message(status);
    device_name = TFE_OpGetDevice(matmul, status);
    ASSERT_TRUE(strstr(device_name, "CPU:0") != nullptr);
  }

}

TEST_P(ModularFileSystemTest, TestFilesExistsNoFiles) {
  const std::vector<std::string> filenames = {};
  EXPECT_TRUE(env_->FilesExist(filenames, /*status=*/nullptr));

  std::vector<Status> statuses;
  EXPECT_TRUE(env_->FilesExist(filenames, &statuses));
  EXPECT_TRUE(statuses.empty());
}

TEST_P(ModularFileSystemTest, TestStatEmptyFile) {
  const std::string filepath = GetURIForPath("a_file");