define and test a regex pattern that matches valid floating point number strings

test_floating_point_number_re_pattern.py

# test_floating_point_number_re_pattern.py
# Rudi Farkas 19 Nov 2013

import re

# define a regex pattern that matches valid floating point number strings
floating_point_number_re_pattern = fpn_rpat = "[-+]?\s*(?:\d+(?:\.(?:\d+)?)?|\.\d+)(?:[eE][-+]\d+)?"


if __name__ == '__main__':
    import unittest
    class Test_fp(unittest.TestCase):

        # compile it into a regex and test it

        def setUp(self):
            self.re = re.compile('and the number is (?P<nbr>{0}),'.format(fpn_rpat))

        def test_number_1(self):
            s = 'and the number is 42, as expected'
            m = self.re.search(s)
            self.assertEqual(42, float(m.groupdict()['nbr']))

        def test_number_2(self):
            s = 'and the number is 42.3, as expected'
            m = self.re.search(s)
            self.assertEqual(42.3, float(m.groupdict()['nbr']))

        def test_number_3(self):
            s = 'and the number is -42.31, as expected'
            m = self.re.search(s)
            self.assertEqual(-42.31, float(m.groupdict()['nbr']))

        def test_number_4(self):
            s = 'and the number is +42.31, as expected'
            m = self.re.search(s)
            self.assertEqual(42.31, float(m.groupdict()['nbr']))

        def test_number_5(self):
            s = 'and the number is 6., as expected'
            m = self.re.search(s)
            self.assertEqual(6, float(m.groupdict()['nbr']))
    
        def test_number_6(self):
            s = 'and the number is .6, as expected'
            m = self.re.search(s)
            self.assertEqual(0.6, float(m.groupdict()['nbr']))

        def test_number_7(self):
            s = 'and the number is -42e-07, as expected'
            m = self.re.search(s)
            self.assertEqual(-42e-07, float(m.groupdict()['nbr']))

        def test_number_8(self):
            s = 'and the number is 42.3e+07, as expected'
            m = self.re.search(s)
            self.assertEqual(42.3e7, float(m.groupdict()['nbr']))

        def test_number_9(self):
            s = 'and the number is -42.3e-07, as expected'
            m = self.re.search(s)
            self.assertEqual(-42.3e-7, float(m.groupdict()['nbr']))

    unittest.main()