The Spaniard missed the first test in order to focus on his training, as team-mate Felipe Massa and tester Pedro de la Rosa took the reins of the new F138 in Jerez.
The second test starts on Tuesday at the Circuit de Catalunya in Barcelona and Ferrari expect Alonso to impress, after Massa set the fastest time overall from the four days in Jerez.
Ferrari said on their official website: "Fernando has maximised the time available and tackled the task with great dedication, performing a focused physical preparation worthy of the best Olympic athlete by alternating between gym sessions, running and biking.
"Now Fernando is ready to slip into the cockpit of the F138 and benefit from all the work of Felipe and Pedro in Andalusia.
"This week it will be the Brazilian (Massa) to sit out for the first three days, with the handover from his team-mate scheduled on Friday."