Temporary Emergency Scheduling and Testing of Fentanyl Analogues Act of 2023 or the TEST Act This bill provides for the rescheduling or removal from scheduling of certain fentanyl-related substances under the Controlled Substances Act. Specifically, the bill requires the Drug Enforcement Administration (DEA) to schedule, reschedule, or remove from scheduling fentanyl-related substances it has identified but not yet permanently scheduled within one year of the bill's enactment. The DEA must schedule, reschedule, or remove from scheduling any new fentanyl-related substances that it identifies after the bill's enactment within three years of identification. The DEA may temporarily schedule newly identified fentanyl-related substances under schedule I for up to three years. The bill provides for the rescheduling of fentanyl-related substances to lower schedules, or for their removal from scheduling altogether, based on appropriate scientific and medical evaluations from the Department of Health and Human Services. The bill also provides for expedited registrations to research schedule I controlled substances, including by allowing for the continuation and consolidation of research under a single registration.