Exercism v3 launches on Sept 1st 2021. Learn more! ðŸš€ðŸš€ðŸš€

Published at Jul 13 2018
·
1 comment

Instructions

Test suite

Solution

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?"
- "Grade 1: Anna, Barb, and Charlie. Grade 2: Alex, Peter, and Zoe. Grade 3â€¦"

Note that all our students only have one name. (It's a small town, what do you want?)

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?

For installation and learning resources, refer to the exercism help page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

```
gem install minitest
```

If you would like color output, you can `require 'minitest/pride'`

in
the test file, or note the alternative instruction, below, for running
the test file.

Run the tests from the exercise directory using the following command:

```
ruby grade_school_test.rb
```

To include color from the command line:

```
ruby -r minitest/pride grade_school_test.rb
```

A pairing session with Phil Battos at gSchool http://gschool.it

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
require 'minitest/autorun'
require_relative 'grade_school'
class SchoolTest < Minitest::Test
def test_empty_grade
school = School.new
expected = []
assert_equal expected, school.students(1)
end
def test_add_student
skip
school = School.new
assert school.add('Aimee', 2)
expected = ['Aimee']
assert_equal expected, school.students(2)
end
def test_add_students_to_different_grades
skip
school = School.new
school.add('Aimee', 3)
school.add('Beemee', 7)
assert_equal ['Aimee'], school.students(3)
assert_equal ['Beemee'], school.students(7)
end
def test_grade_with_multiple_students
skip
school = School.new
grade = 6
students = %w(Aimee Beemee Ceemee)
students.each { |student| school.add(student, grade) }
assert_equal students, school.students(grade)
end
def test_grade_with_multiple_students_sorts_correctly
skip
school = School.new
grade = 6
students = %w(Beemee Aimee Ceemee)
students.each { |student| school.add(student, grade) }
expected = students.sort
assert_equal expected, school.students(grade)
end
def test_empty_students_by_grade
skip
school = School.new
expected = []
assert_equal expected, school.students_by_grade
end
def test_students_by_grade
skip
school = School.new
grade = 6
students = %w(Beemee Aimee Ceemee)
students.each { |student| school.add(student, grade) }
expected = [{ grade: grade, students: students.sort }]
assert_equal expected, school.students_by_grade
end
def test_students_by_grade_sorted
skip
school = School.new
everyone.each do |grade|
grade[:students].each { |student| school.add(student, grade[:grade]) }
end
expected = everyone_sorted
assert_equal expected, school.students_by_grade
end
def everyone
[
{ grade: 3, students: %w(Deemee Eeemee) },
{ grade: 1, students: %w(Effmee Geemee) },
{ grade: 2, students: %w(Aimee Beemee Ceemee) }
]
end
def everyone_sorted
[
{ grade: 1, students: %w(Effmee Geemee) },
{ grade: 2, students: %w(Aimee Beemee Ceemee) },
{ grade: 3, students: %w(Deemee Eeemee) }
]
end
# Problems in exercism evolve over time, as we find better ways to ask
# questions.
# The version number refers to the version of the problem you solved,
# not your solution.
#
# Define a constant named VERSION inside of the top level BookKeeping
# module, which may be placed near the end of your file.
#
# In your file, it will look like this:
#
# module BookKeeping
# VERSION = 2 # Where the version number matches the one in the test.
# end
#
# If you are curious, read more about constants on RubyDoc:
# http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html
def test_bookkeeping
skip
assert_equal 3, BookKeeping::VERSION
end
end
```

```
# School
class School
attr_accessor :db
def initialize
@db = Hash.new([])
end
def add(name, grade)
db[grade] = [] unless db.key?(grade)
(db[grade] << name).sort!
end
def grade(grade)
db[grade]
end
def to_hash
Hash[db.sort]
end
end
```

A huge amount can be learned from reading other peopleâ€™s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

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## Community comments

Do you think it's a good idea having your :db accessible to the outside world? Also, does it need to be an accessor? Are you ever doing db = anywhere?