http://admission.universityofcalifornia.edu/counselors/files/quick-reference-2017.pdf (page 12 and 14) suggests that the following are roughly equivalent for the purpose of satisfying UC frosh entrance requirements in language other than English:
- Completion of second year of US high school regular Spanish course.
- 520 on SAT subject test in Spanish.
- 6th grade in a non-US school where Spanish is the primary language of instruction.
https://collegereadiness.collegeboard.org/sat-subject-tests/subjects/languages/spanish has some SAT subject test practice questions.
There may be other Spanish tests on the web:
https://www.fu-tenerife.com/spanish-proficiency-tests/
https://www.lengalia.com/en/placement-test.html
https://www.transparent.com/learn-spanish/proficiency-test.html