// Test not found errors in TF_Operation*() query functions.
  EXPECT_EQ(-1, TF_OperationOutputListLength(feed, "bogus", s));
  EXPECT_EQ(TF_INVALID_ARGUMENT, TF_GetCode(s));

  ASSERT_FALSE(GetAttrValue(feed, "missing", &attr_value, s));
  EXPECT_EQ(string("Operation 'feed' has no attr named 'missing'."),
            string(TF_Message(s)));

  // Make a constant oper with the scalar "3".