Leadership is tested in the UPSC process through the written exam and interview stages by evaluating candidates' ability to communicate effectively and make informed decisions. In the written stage, essays and case studies may require demonstrating leadership qualities such as strategic thinking, vision, and ethical considerations. In the interview phase, panelists assess candidates' leadership potential through situational questions and their responses to current affairs. Candidates must showcase qualities like decision-making, teamwork, and adaptability, reflecting the principles of effective leadership required in civil service.