A4 portrait - PET: Python Entre Todos - Python Argentina

How should the test be? 16
raise NotQuadratic()
discriminant = b * b - 4 * a * c
if discriminant < 0:
raise NoRealRoots()
root_discriminant = math.sqrt(discriminant)
first_root = (-1 * b + root_discriminant) / (2 * a)
second_root = (-1 * b - root_discriminant) / (2 * a)
# min y max are python functions
chico = min(first_root, second_root)
grande = max(first_root, second_root)
return (chico, grande)
def find_coefficients(first_root, second_root):
"""Given the roots of a quadratic function, return the coefficients.
The quadratic function is given by:
(x - r1) * (x - r2) = 0
"""
# You can reach this result by applying distribution
return (1, -1 * (first_root + second_root), first_root * second_root)
Finally, let’s see the tests we wrote for that code:
import unittest
from polynomial import find_roots, find_coefficients, \
NotQuadratic, NoRealRoots
class Testpolynomial(unittest.TestCase):
def test_find_roots(self):
COEFFICIENTS_ROOTS = [
((1,0,0), (0, 0)),
((-1,1,2), (-1, 2)),
((-1,0,4), (-2, 2)),
]
for coef, expected_roots in COEFFICIENTS_ROOTS:
roots = find_roots(coef[0], coef[1], coef[2])
self.assertEquals(roots, expected_roots)
def test_form_polynomial(self):
RAICES_COEFFICIENTS = [
((1, 1), (1, -2, 1)),
((0, 0), (1, 0, 0)),
((2, -2), (1, 0, -4)),
((-4, 3), (1, 1, -12)),
]
for roots, expected_coefficients in RAICES_COEFFICIENTS:
coefficients = find_coefficients(roots[0], roots[1])
self.assertEquals(coefficients, expected_coefficients)
def test_cant_find_roots(self):
self.assertRaises(NoRealRoots, find_roots, 1, 0, 4)
def test_not_quadratic(self):
self.assertRaises(NotQuadratic, find_roots, 0, 2, 3)
PET: English Translation (Issue 1, August 2010) — http://revista.python.org.ar