One advantage of Common Core is that by requiring certain common standards, it will ease the transition for students and families who move into a new school district anywhere in the country.
Whether or not Common Core is adopted, teachers should be tested. If students are expected to keep up with new material, it is even more important that teachers be tested to make certain that they have kept current in their field of instruction.
Teacher testing will help administrators determine which teachers need additional preparation before the next academic year.
If testing is good for students, it is also good for teachers.