The Belfast boxer was less than impressed at the timing of the drug testing, given the nature of boxing and the preparations involved.
"Anti-doping has decided to hit me with a urine test three days before the weigh-in and after dehydrating myself making weight!" Barnes tweeted.
"I can't even drink ..."
The Olympic bronze medallist, who picked up gold in the 2010 Commonwealth Games, also voiced concerns that being taken straight from training without being allowed to shower could lead to illness.
"Supposed to be fighting in a few days!" Barnes added.
"Could have tested me at a reasonable time of the day when I wasn't just finished training."
And apparently things went from bad to worse.
Barnes further tweeted that he had only been allowed to leave at 2am, but was then woken up at 7.30am for another test.
"This is some preparation for the games," he added, complete with expletive.
Teammate Michael Conlan also tweeted similar concerns about the experience.