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lujanfernaud's solution

to Grade School in the Ruby Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

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?)

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?


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

Source

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

Submitting Incomplete Solutions

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

grade_school_test.rb

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
class School
  def initialize
    @students = Hash.new([])
  end

  def add(name, grade)
    (@students[grade] += [name]).sort!
  end

  def students(grade)
    @students[grade]
  end

  def students_by_grade
    @students.sort.map(&by_grade)
  end

  private

  def by_grade
    proc { |grade, students| { grade: grade, students: students } }
  end
end

module BookKeeping
  VERSION = 3
end

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