Testing Framework

[remdesivir6]

I am wondering what is the recommended approach for unit testing of model components.

Consider the following model.py from the Getting Started section of the documentation.

 from cashflower import variable

 @variable()
 def age(t):
     if t == 0:
         return int(main.get("AGE"))
     elif t % 12 == 0:
         return age(t-1) + 1
     else:
         return age(t-1)


 @variable()
 def death_prob(t):
     if age(t) == age(t-1):
         return death_prob(t-1)
     elif age(t) <= 100:
         sex = main.get("SEX")
         yearly_rate = assumption["mortality"].loc[age(t)][sex]
         monthly_rate = (1 - (1 - yearly_rate)**(1/12))
         return monthly_rate
     else:
         return 1

one idea is to make use of patching in this way:

import unittest
from unittest.mock import patch

import pandas as pd
from cashflower import variable  # noqa
from input import main 
from model import *


class TestAgeVariable(unittest.TestCase):

    @patch.object(main, 'get', return_value=30)
    def test_age_at_t_zero(self, mock_get):
        self.assertEqual(age.func(0), 30)

    @patch.object(main, 'get', return_value=30)
    def test_age_at_t_twelve(self, mock_get):
        self.assertEqual(age.func(12), 31)

    @patch.object(main, 'get', return_value=30)
    def test_age_at_t_not_twelve(self, mock_get):
        self.assertEqual(age.func(11), 30)


class TestDeathProbVariable(unittest.TestCase):

    @patch.object(main, 'get', return_value='M')
    @patch.dict('input.assumption', {'mortality': pd.DataFrame({'M': [0.01]}, index=[30])})
    def test_death_prob_at_t_zero(self, mock_get):
        self.assertEqual(death_prob.func(0), 0.01)

    @patch.object(main, 'get', return_value='M')
    @patch.dict('input.assumption', {'mortality': pd.DataFrame({'M': [0.01, 0.02]}, index=[30, 31])})
    def test_death_prob_at_t_twelve(self, mock_get):
        self.assertEqual(death_prob.func(12), 0.02)

    @patch.object(main, 'get', return_value='M')
    @patch.dict('input.assumption', {'mortality': pd.DataFrame({'M': [0.01]}, index=[30])})
    def test_death_prob_at_t_not_twelve(self, mock_get):
        self.assertEqual(death_prob.func(11), 0.01)

is there a better way?

[zchmielewska]

Hi @mtaczynski, thanks for sharing your approach to unit testing of cash flow models. It's awesome!

I will also share if I think of or find any other approach.