def test_parse_from_string_is_correct(self):
with self.subTest('Coeff is 0'):
s = '0'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=0, variable=None, power=0))
with self.subTest('Coeff is 1'):
s = 'x^2'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=1, variable='x', power=2))
with self.subTest('Power is 0'):
s = '2'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=2, variable=None, power=0))
with self.subTest('Power is 1'):
s = '2*x'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=2, variable='x', power=1))
with self.subTest('Coeff is 1 and power is 1'):
s = 'x'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=1, variable='x', power=1))
with self.subTest(
'Coeff is greater than 1 and power is greater than 1'):
s = '2*x^2'
self.assertEqual(Term.parse_from_string(s),
Term(coeff=2, variable='x', power=2))
def parse_from_string(cls, s):
unparsed_terms = s.split('+')
terms = [Term.parse_from_string(t) for t in unparsed_terms]
return cls(terms)
