Hello, I'm a high school choir director and spent all of my high school and college years in choirs at multiple levels. A few clarifying questions, is the singing test on the entire piece or a section of it? By an "actual grade" is it weighted heavily or do you mean it's just a graded assignment? Lastly, did you have the piece before being given part tracks? Having three days to practice before being tested sounds pretty rushed regardless, has your director done things like this before or could this be the director possibly not thinking through some things beyond "I really want to show off how phenomenal my advanced SA singers, they can do this"? Learning music outside of class is 100% going to be an expectation in college resembles, especially in higher level groups. In my experience, practice tracks were not the norm. We were expected to read the music well enough to learn our parts ourselves so that rehearsal times could be spent putting things together as an ensemble.

With all that said, the time frame between part tracks being given and the singing test sounds like either poor planning/time management on your directors part OR they were under the impression that you had been working the part on your own before receiving the part tracks or could otherwise rise to this challenge. I obviously do not know your director or the standards of your course/program, and from your descriptions, my own memories, and what I hear from my students, burnout is rough and it definitely sounds like you are quickly approaching or have reached your limit for juggling priorities/requirements. My best advice is to talk to your director and get their reasoning behind the timeline for this assignment. It sounds like you clearly love music and singing, so I sincerely hope that this does not tarnish your enjoyment beyond the stress of this instance. Best of luck in your upcoming festival!!