Published at Nov 15 2019
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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 3…"

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 Ruby resources 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
end
```

```
=begin
Write your code for the 'Grade School' exercise in this file. Make the tests in
`grade_school_test.rb` pass.
To get started with TDD, see the `README.md` file in your
`ruby/grade-school` directory.
=end
# Elapsed time: ~ 30 mins
class Klass
def self.find_or_initialize_by(school:, num:)
school.klasses.find { |k| k.num == num } || self.new(school, num)
end
def initialize(school, num)
@school = school
@num = num
@students = []
end
attr_reader :school, :num, :students
def add(student)
@students << student
student
end
end
class School
def initialize
@klasses = []
end
def students(klass_num)
Klass.find_or_initialize_by(school: self, num: klass_num).students.sort
end
def add(student, klass_num)
klass = Klass.find_or_initialize_by(school: self, num: klass_num)
klass.add(student)
klasses.push(klass) unless klasses.include?(klass)
end
def students_by_grade
klasses.sort_by(&:num).map { |k| { grade: k.num, students: k.students.sort } }
end
attr_reader :klasses
end
```

A huge amount can be learned from reading other people’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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