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36828b106f
Current implementation is buggy and hard to read. * Negative values were raising a TypeError due to `math.sqrt` * 1 was considered prime, it is not. * 2 was considered not prime, it is. The implementation has been corrected to fix the bugs and to enhance readability. A docstring has been added with the definition of a prime number. A complete test suite has been written, it tests the 10 first primes, a negative value, 0, 1 and some not prime numbers. closes #795
55 lines
1.6 KiB
Python
55 lines
1.6 KiB
Python
import math
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import unittest
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def primeCheck(number):
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"""
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A number is prime if it has exactly two dividers: 1 and itself.
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"""
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if number < 2:
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# Negatives, 0 and 1 are not primes
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return False
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if number < 4:
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# 2 and 3 are primes
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return True
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if number % 2 == 0:
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# Even values are not primes
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return False
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# Except 2, all primes are odd. If any odd value divide
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# the number, then that number is not prime.
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odd_numbers = range(3, int(math.sqrt(number)) + 1, 2)
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return not any(number % i == 0 for i in odd_numbers)
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class Test(unittest.TestCase):
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def test_primes(self):
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self.assertTrue(primeCheck(2))
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self.assertTrue(primeCheck(3))
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self.assertTrue(primeCheck(5))
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self.assertTrue(primeCheck(7))
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self.assertTrue(primeCheck(11))
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self.assertTrue(primeCheck(13))
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self.assertTrue(primeCheck(17))
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self.assertTrue(primeCheck(19))
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self.assertTrue(primeCheck(23))
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self.assertTrue(primeCheck(29))
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def test_not_primes(self):
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self.assertFalse(primeCheck(-19),
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"Negative numbers are not prime.")
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self.assertFalse(primeCheck(0),
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"Zero doesn't have any divider, primes must have two")
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self.assertFalse(primeCheck(1),
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"One just have 1 divider, primes must have two.")
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self.assertFalse(primeCheck(2 * 2))
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self.assertFalse(primeCheck(2 * 3))
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self.assertFalse(primeCheck(3 * 3))
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self.assertFalse(primeCheck(3 * 5))
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self.assertFalse(primeCheck(3 * 5 * 7))
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if __name__ == '__main__':
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unittest.main()
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