Python: grade_school

.gitignore

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 *.swp
 *.swo
 **/__pycache__/
+**/.mypy_cache/

python/grade-school/.exercism/metadata.json

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+{"track":"python","exercise":"grade-school","id":"0a07ce0d313a4fc7895b13247af40fe6","url":"https://exercism.io/my/solutions/0a07ce0d313a4fc7895b13247af40fe6","handle":"DmitryKokorin","is_requester":true,"auto_approve":false}

python/grade-school/README.md

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+# Grade 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:
+
+- 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?
+
+
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you should write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+## Running the tests
+
+To run the tests, run `pytest grade_school_test.py`
+
+Alternatively, you can tell Python to run the pytest module:
+`python -m pytest grade_school_test.py`
+
+### Common `pytest` options
+
+- `-v` : enable verbose output
+- `-x` : stop running tests on first failure
+- `--ff` : run failures from previous test before running other test cases
+
+For other options, see `python -m pytest -h`
+
+## Submitting Exercises
+
+Note that, when trying to submit an exercise, make sure the solution is in the `$EXERCISM_WORKSPACE/python/grade-school` directory.
+
+You can find your Exercism workspace by running `exercism debug` and looking for the line that starts with `Workspace`.
+
+For more detailed information about running tests, code style and linting,
+please see [Running the Tests](http://exercism.io/tracks/python/tests).
+
+## Source
+
+A pairing session with Phil Battos at gSchool [http://gschool.it](http://gschool.it)
+
+## Submitting Incomplete Solutions
+
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

python/grade-school/grade_school.py

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+import bisect
+from collections import defaultdict
+from typing import List, DefaultDict
+
+
+class School:
+    def __init__(self) -> None:
+        self.student_db: DefaultDict[int, List[str]] = defaultdict(list)
+
+    def add_student(self, name: str, grade: int) -> None:
+        bisect.insort(self.student_db[grade], name)
+
+    def grade(self, grade_number: int) -> List[str]:
+
+        if grade_number not in self.student_db.keys():
+            return []
+
+        return self.student_db[grade_number]
+
+    def roster(self) -> List[str]:
+        return sum([self.grade(grade_number) for grade_number
+                    in sorted(self.student_db)], [])

python/grade-school/grade_school_test.py

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+import unittest
+
+from grade_school import School
+
+# Tests adapted from `problem-specifications//canonical-data.json`
+
+
+class GradeSchoolTest(unittest.TestCase):
+    def test_adding_a_student_adds_them_to_the_sorted_roster(self):
+        school = School()
+        school.add_student(name="Aimee", grade=2)
+        expected = ["Aimee"]
+        self.assertEqual(school.roster(), expected)
+
+    def test_adding_more_student_adds_them_to_the_sorted_roster(self):
+        school = School()
+        school.add_student(name="Blair", grade=2)
+        school.add_student(name="James", grade=2)
+        school.add_student(name="Paul", grade=2)
+        expected = ["Blair", "James", "Paul"]
+        self.assertEqual(school.roster(), expected)
+
+    def test_adding_students_to_different_grades_adds_them_to_the_same_sorted_roster(
+        self
+    ):
+        school = School()
+        school.add_student(name="Chelsea", grade=3)
+        school.add_student(name="Logan", grade=7)
+        expected = ["Chelsea", "Logan"]
+        self.assertEqual(school.roster(), expected)
+
+    def test_roster_returns_an_empty_list_if_there_are_no_students_enrolled(self):
+        school = School()
+        expected = []
+        self.assertEqual(school.roster(), expected)
+
+    def test_student_names_with_grades_are_displayed_in_the_same_sorted_roster(self):
+        school = School()
+        school.add_student(name="Peter", grade=2)
+        school.add_student(name="Anna", grade=1)
+        school.add_student(name="Barb", grade=1)
+        school.add_student(name="Zoe", grade=2)
+        school.add_student(name="Alex", grade=2)
+        school.add_student(name="Jim", grade=3)
+        school.add_student(name="Charlie", grade=1)
+        expected = ["Anna", "Barb", "Charlie", "Alex", "Peter", "Zoe", "Jim"]
+        self.assertEqual(school.roster(), expected)
+
+    def test_grade_returns_the_students_in_that_grade_in_alphabetical_order(self):
+        school = School()
+        school.add_student(name="Franklin", grade=5)
+        school.add_student(name="Bradley", grade=5)
+        school.add_student(name="Jeff", grade=1)
+        expected = ["Bradley", "Franklin"]
+        self.assertEqual(school.grade(5), expected)
+
+    def test_grade_returns_an_empty_list_if_there_are_no_students_in_that_grade(self):
+        school = School()
+        expected = []
+        self.assertEqual(school.grade(1), expected)
+
+
+if __name__ == "__main__":
+    unittest.main()