std::unordered_map<string, string> clusters = GetClusters(*graph);
  EXPECT_NE(clusters["MatMul0_dev0"], clusters["MatMul1_dev1"]);
  EXPECT_NE(clusters["MatMulCombined_dev1"], clusters["MatMul0_dev0"]);
  EXPECT_NE(clusters["MatMulCombined_dev1"], clusters["MatMul1_dev1"]);
  EXPECT_EQ(clusters["A_dev0"], clusters["MatMul0_dev0"]);
  EXPECT_EQ(clusters["B_dev1"], clusters["MatMul1_dev1"]);
}