Method test_choices

Lib/test/test_random.py:261–337

(self)

            sample('x', 1, counts=[0])

    def test_choices(self):
        choices = self.gen.choices
        data = ['red', 'green', 'blue', 'yellow']
        str_data = 'abcd'
        range_data = range(4)
        set_data = set(range(4))

        # basic functionality
        for sample in [
            choices(data, k=5),
            choices(data, range(4), k=5),
            choices(k=5, population=data, weights=range(4)),
            choices(k=5, population=data, cum_weights=range(4)),
            choices(data, k=MyIndex(5)),
        ]:
            self.assertEqual(len(sample), 5)
            self.assertEqual(type(sample), list)
            self.assertTrue(set(sample) <= set(data))

        # test argument handling
        with self.assertRaises(TypeError):                               # missing arguments
            choices(2)

        self.assertEqual(choices(data, k=0), [])                         # k == 0
        self.assertEqual(choices(data, k=-1), [])                        # negative k behaves like ``[0] * -1``
        with self.assertRaises(TypeError):
            choices(data, k=2.5)                                         # k is a float

        self.assertTrue(set(choices(str_data, k=5)) <= set(str_data))    # population is a string sequence
        self.assertTrue(set(choices(range_data, k=5)) <= set(range_data))  # population is a range
        with self.assertRaises(TypeError):
            choices(set_data, k=2)                                       # population is not a sequence

        self.assertTrue(set(choices(data, None, k=5)) <= set(data))      # weights is None
        self.assertTrue(set(choices(data, weights=None, k=5)) <= set(data))
        with self.assertRaises(ValueError):
            choices(data, [1,2], k=5)                                    # len(weights) != len(population)
        with self.assertRaises(TypeError):
            choices(data, 10, k=5)                                       # non-iterable weights
        with self.assertRaises(TypeError):
            choices(data, [None]*4, k=5)                                 # non-numeric weights
        for weights in [
                [15, 10, 25, 30],                                                 # integer weights
                [15.1, 10.2, 25.2, 30.3],                                         # float weights
                [Fraction(1, 3), Fraction(2, 6), Fraction(3, 6), Fraction(4, 6)], # fractional weights
                [True, False, True, False]                                        # booleans (include / exclude)
        ]:
            self.assertTrue(set(choices(data, weights, k=5)) <= set(data))

        with self.assertRaises(ValueError):
            choices(data, cum_weights=[1,2], k=5)                        # len(weights) != len(population)
        with self.assertRaises(TypeError):
            choices(data, cum_weights=10, k=5)                           # non-iterable cum_weights
        with self.assertRaises(TypeError):
            choices(data, cum_weights=[None]*4, k=5)                     # non-numeric cum_weights
        with self.assertRaises(TypeError):
            choices(data, range(4), cum_weights=range(4), k=5)           # both weights and cum_weights
        for weights in [