The Colombian injured his left shoulder when he crashed while riding on a dirt track.
"Examinations showed microfractures without any lesions to ligaments and tendons," said a Pramac statement. "Recovery time is estimated at three weeks."
Ducati's factory test rider Michele Pirro will replace Hernandez for the February 4-7 test at Sepang.
In 2013, Pirro made several racing appearances for the team replacing injured Ben Spies.
Pramac say they are confident that Hernandez will be fit for the second winter test on February 23-26 also at Sepang.