Roman Numerals

app.py

from flask import Flask

from roman_numerals import add


app = Flask(__name__)

@app.route('/add/<a>/<b>')
def add_endpoint(a, b):
    return f'Answer: {add(a, b)}'

roman_numerals.py

def add(a, b):
    expanded = {
        'V': 'IIIII',
        'IV': 'IIII',
    }
    expanded_a = expanded.get(a, a)
    expanded_b = expanded.get(b, b)

    combo = expanded_a + expanded_b

    special_cases = {
        'IIIIIIIIII': 'X',
        'IIIIII': 'VI',
        'IIIII': 'V',
        'VV': 'X',
        'XXXXX': 'L',
        'LL': 'C',
    }

    result = special_cases.get(combo, combo)
    return result

test_roman_numerals.py

import requests

from roman_numerals import add


class TestUnit:

    def test_add_one_and_one(self):
        assert add('I', 'I') == 'II'

    def test_make_five(self):
        assert add('I', 'IIII') == 'V'

    def test_make_ten(self):
        assert add('V', 'V') == 'X'

    def test_make_fifty(self):
        assert add('XX', 'XXX') == 'L'

    def test_make_one_hundred(self):
        assert add('L', 'L') == 'C'

    def test_make_six(self):
        assert add('V', 'I') == 'VI'
        assert add('I', 'V') == 'VI'
        assert add('III', 'III') == 'VI'

    def test_accept_four(self):
        assert add('IV', 'I') == 'V'


class TestE2E:

    def test_response(self):
        r = requests.get('http://localhost:5000/add/I/I')

        assert r.status_code == 200
        assert r.text == 'Answer: II'

    def test_stringify(self):
        r = requests.get('http://localhost:5000/add/5/5')

        assert r.text == 'Answer: 55'

    def test_vv(self):
        r = requests.get('http://localhost:5000/add/v/v')

        assert r.text == 'Answer: X'