This study considers ways that the proposed Engineering Test Reactor (ETR), or the proposed International Tokamak Reactor (INTOR), can be used for magnet performance tests that would be useful for the design and operation of the Demonstration Tokamak Power Plant (DEMO). Such testing must not interfere with the main function of the ETR/INTOR as an integrated fusion reactor. A performance test plan for the ETR/INTOR magnets is proposed and appropriate tests on the magnets for each phase of the ETR/INTOR operation are described. The suggested tests would verify design requirements and monitor long-term changes due to radiation. This paper also summarizes the design and operational performance of existing superconducting magnets and identifies the known failures and their predominant causes. In addition, existing radiation dose-damage information and criteria that relate material property change with component failure are combined with predicted neutron and gamma dose rates at the ETR/INTOR magnet position to estimate the time to insulator and conductor failure in this reactor. Long-term operation of magnets in a pulsed plasma environment such as in the ETR/INTOR, however, may aggravate the effect of gamma and neutron radiation on the insulators. To provide more accurate time-to-failure information for magnet component material, accelerated irradiation of magnet material coupons in the ETR/INTOR and in other irradiation facilities is suggested.