Grade School

Instructions

Given students' names along with the grade that they are in, create a roster for the school.

In the end, you should be able to:

• Add a student's name to the roster for a grade
  • "Add Jim to grade 2."
  • "OK."
• Get a list of all students enrolled in a grade
  • "Which students are in grade 2?"
  • "We've only got Jim just now."
• Get a sorted list of all students in all grades. Grades should sort as 1, 2, 3, etc., and students within a grade should be sorted alphabetically by name.
  • "Who all is enrolled in school right now?"
  • "Let me think. We have Anna, Barb, and Charlie in grade 1, Alex, Peter, and Zoe in grade 2 and Jim in grade 5. So the answer is: Anna, Barb, Charlie, Alex, Peter, Zoe and Jim"

Note that all our students only have one name (It's a small town, what do you want?) and each student cannot be added more than once to a grade or the roster. In fact, when a test attempts to add the same student more than once, your implementation should indicate that this is incorrect.

For bonus points

Did you get the tests passing and the code clean? If you want to, these are some additional things you could try:

• If you're working in a language with mutable data structures and your implementation allows outside code to mutate the school's internal DB directly, see if you can prevent this. Feel free to introduce additional tests.

Then please share your thoughts in a comment on the submission. Did this experiment make the code better? Worse? Did you learn anything from it?