def simple_interest(
self,
principal: Dollars,
time: float,
unit: TimeUnit,
) -> Dollars:
""" Compute the interest during the given time """
rate_time_product = math.fabs(self.rate * time)
if self.rate_cycle == unit:
return principal * rate_time_product
try:
time_convert_factor = convert_time(unit, self.rate_cycle)
return principal * rate_time_product * time_convert_factor
except TimeConversionException:
raise ValueError from TimeConversionException
def test_non_conversion(self):
""" Check that when both units are equal, the factor is 1 """
# Group 1
self.assertEqual(1, convert_time(TimeUnit.DAILY, TimeUnit.DAILY))
self.assertEqual(1, convert_time(TimeUnit.WEEKLY, TimeUnit.WEEKLY))
self.assertEqual(1, convert_time(TimeUnit.BI_WEEKLY,
TimeUnit.BI_WEEKLY))
# Group 2
self.assertEqual(1, convert_time(TimeUnit.MONTHLY, TimeUnit.MONTHLY))
self.assertEqual(1, convert_time(TimeUnit.QUARTERLY,
TimeUnit.QUARTERLY))
self.assertEqual(1, convert_time(TimeUnit.ANNUALLY, TimeUnit.ANNUALLY))
def test_accurate_conversions_group1(self):
""" Test the conversion factors within group 1 """
self.assertEqual(1 / 7, convert_time(TimeUnit.DAILY, TimeUnit.WEEKLY))
self.assertEqual(1 / 14,
convert_time(TimeUnit.DAILY, TimeUnit.BI_WEEKLY))
#
self.assertEqual(0.5, convert_time(TimeUnit.WEEKLY,
TimeUnit.BI_WEEKLY))
self.assertEqual(7, convert_time(TimeUnit.WEEKLY, TimeUnit.DAILY))
#
self.assertEqual(2, convert_time(TimeUnit.BI_WEEKLY, TimeUnit.WEEKLY))
self.assertEqual(14, convert_time(TimeUnit.BI_WEEKLY, TimeUnit.DAILY))
def test_accurate_conversions_group2(self):
""" Test the conversion factors within group 2 """
self.assertEqual(1 / 3,
convert_time(TimeUnit.MONTHLY, TimeUnit.QUARTERLY))
self.assertEqual(1 / 12,
convert_time(TimeUnit.MONTHLY, TimeUnit.ANNUALLY))
#
self.assertEqual(3, convert_time(TimeUnit.QUARTERLY, TimeUnit.MONTHLY))
self.assertEqual(1 / 4,
convert_time(TimeUnit.QUARTERLY, TimeUnit.ANNUALLY))
#
self.assertEqual(12, convert_time(TimeUnit.ANNUALLY, TimeUnit.MONTHLY))
self.assertEqual(4, convert_time(TimeUnit.ANNUALLY,
TimeUnit.QUARTERLY))
def test_inaccurate_conversion(self):
""" Any conversion between the two groups is inaccurate """
for unit_1 in time_unit.TIME_GROUP_1:
for unit_2 in time_unit.TIME_GROUP_2:
with self.assertRaises(TimeConversionException):
convert_time(unit_1, unit_2)