TEST_F(AsStringGraphTest, Complex) {
  TF_ASSERT_OK(Init(DT_COMPLEX64, /*fill=*/"", /*width=*/5, /*precision=*/2));

  AddInputFromArray<complex64>(TensorShape({3}), {{-4, 2}, {0}, {3.14159, -1}});
  TF_ASSERT_OK(RunOpKernel());
  Tensor expected(allocator(), DT_STRING, TensorShape({3}));
  test::FillValues<tstring>(
      &expected, {"(-4.00, 2.00)", "( 0.00, 0.00)", "( 3.14,-1.00)"});
  test::ExpectTensorEqual<tstring>(expected, *GetOutput(0));
}
The software uses a function that accepts a format string as an argument, but the format string originates from an external source.