Reimplement grade-school based on problem-specifications

The upstream specification has undergone significant changes.
This generates a new test suite based on the changed specification,
and reimplements the sample solution to pass the new tests.

Author: kytrinyx

exercises/practice/grade-school/.docs/instructions.md

@@ -1,7 +1,6 @@
 # Instructions
 
-Given students' names along with the grade that they are in, create a roster
-for the school.
+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:
 
@@ -11,28 +10,12 @@ In the end, you should be able to:
 - 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.
+- 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"
+  - "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?)
-
-## 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?
+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.

exercises/practice/grade-school/.meta/config.json

@@ -1,5 +1,5 @@
 {
-  "blurb": "Given students' names along with the grade that they are in, create a roster for the school",
+  "blurb": "Given students' names along with the grade that they are in, create a roster for the school.",
   "authors": [
     "kytrinyx"
   ],
@@ -29,6 +29,5 @@
       ".meta/example.rb"
     ]
   },
-  "source": "A pairing session with Phil Battos at gSchool",
-  "source_url": "http://gschool.it"
+  "source": "A pairing session with Phil Battos at gSchool"
 }

exercises/practice/grade-school/.meta/example.rb

@@ -3,20 +3,22 @@ def initialize
     @students = Hash.new { |hash, key| hash[key] = [] }
   end
 
-  def students_by_grade
-    @students.keys.sort.map { |level| grade(level) }
+  def add(student, grade)
+    if roster.include?(student)
+      return false
+    end
+    students[grade] << student
+    true
   end
 
-  def add(student, level)
-    @students[level] << student
-    @students[level].sort!
+  def roster
+    students.sort_by {|grade, names| grade}.map {|_, names| names.sort}.flatten
   end
 
-  def students(level)
-    @students[level]
+  def grade(number)
+    students[number].sort
   end
 
-  def grade(level)
-    { grade: level, students: students(level) }
-  end
+  private
+  attr_reader :students
 end

exercises/practice/grade-school/.meta/tests.toml

@@ -9,23 +9,78 @@
 # As user-added comments (using the # character) will be removed when this file
 # is regenerated, comments can be added via a `comment` key.
 
+[a3f0fb58-f240-4723-8ddc-e644666b85cc]
+description = "Roster is empty when no student is added"
+
+[9337267f-7793-4b90-9b4a-8e3978408824]
+description = "Add a student"
+
 [6d0a30e4-1b4e-472e-8e20-c41702125667]
-description = "Adding a student adds them to the sorted roster"
+description = "Student is added to the roster"
+
+[73c3ca75-0c16-40d7-82f5-ed8fe17a8e4a]
+description = "Adding multiple students in the same grade in the roster"
 
 [233be705-dd58-4968-889d-fb3c7954c9cc]
-description = "Adding more student adds them to the sorted roster"
+description = "Multiple students in the same grade are added to the roster"
+
+[87c871c1-6bde-4413-9c44-73d59a259d83]
+description = "Cannot add student to same grade in the roster more than once"
+
+[c125dab7-2a53-492f-a99a-56ad511940d8]
+description = "A student can't be in two different grades"
+include = false
+
+[a0c7b9b8-0e89-47f8-8b4a-c50f885e79d1]
+description = "A student can only be added to the same grade in the roster once"
+include = false
+reimplements = "c125dab7-2a53-492f-a99a-56ad511940d8"
+
+[d7982c4f-1602-49f6-a651-620f2614243a]
+description = "Student not added to same grade in the roster more than once"
+reimplements = "a0c7b9b8-0e89-47f8-8b4a-c50f885e79d1"
+
+[e70d5d8f-43a9-41fd-94a4-1ea0fa338056]
+description = "Adding students in multiple grades"
 
 [75a51579-d1d7-407c-a2f8-2166e984e8ab]
-description = "Adding students to different grades adds them to the same sorted roster"
+description = "Students in multiple grades are added to the roster"
 
-[a3f0fb58-f240-4723-8ddc-e644666b85cc]
-description = "Roster returns an empty list if there are no students enrolled"
+[7df542f1-57ce-433c-b249-ff77028ec479]
+description = "Cannot add same student to multiple grades in the roster"
 
-[180a8ff9-5b94-43fc-9db1-d46b4a8c93b6]
-description = "Student names with grades are displayed in the same sorted roster"
+[6a03b61e-1211-4783-a3cc-fc7f773fba3f]
+description = "A student cannot be added to more than one grade in the sorted roster"
+include = false
+reimplements = "c125dab7-2a53-492f-a99a-56ad511940d8"
 
-[1bfbcef1-e4a3-49e8-8d22-f6f9f386187e]
-description = "Grade returns the students in that grade in alphabetical order"
+[c7ec1c5e-9ab7-4d3b-be5c-29f2f7a237c5]
+description = "Student not added to multiple grades in the roster"
+reimplements = "6a03b61e-1211-4783-a3cc-fc7f773fba3f"
+
+[d9af4f19-1ba1-48e7-94d0-dabda4e5aba6]
+description = "Students are sorted by grades in the roster"
+
+[d9fb5bea-f5aa-4524-9d61-c158d8906807]
+description = "Students are sorted by name in the roster"
+
+[180a8ff9-5b94-43fc-9db1-d46b4a8c93b6]
+description = "Students are sorted by grades and then by name in the roster"
 
 [5e67aa3c-a3c6-4407-a183-d8fe59cd1630]
-description = "Grade returns an empty list if there are no students in that grade"
+description = "Grade is empty if no students in the roster"
+
+[1e0cf06b-26e0-4526-af2d-a2e2df6a51d6]
+description = "Grade is empty if no students in that grade"
+
+[2bfc697c-adf2-4b65-8d0f-c46e085f796e]
+description = "Student not added to same grade more than once"
+
+[66c8e141-68ab-4a04-a15a-c28bc07fe6b9]
+description = "Student not added to multiple grades"
+
+[c9c1fc2f-42e0-4d2c-b361-99271f03eda7]
+description = "Student not added to other grade for multiple grades"
+
+[1bfbcef1-e4a3-49e8-8d22-f6f9f386187e]
+description = "Students are sorted by name in a grade"