binarySearch.py

import unittest


def contains(ordered_list, number):

    # Check if an integer is present in the list
    if not ordered_list :
        return False # empty list
    left = 0
    right = len(ordered_list)
    mid = (left+right)/2
    while right>left:
        if number == ordered_list[mid]:
            return True
        if number>ordered_list[mid]:
            left = mid+1
            
        else:
            right = mid
        mid = (left+right)/2

    return False


















# Tests

class Test(unittest.TestCase):

    def test_empty_list(self):
        result = contains([], 1)
        self.assertFalse(result)

    def test_one_item_list_number_present(self):
        result = contains([1], 1)
        self.assertTrue(result)

    def test_one_item_list_number_absent(self):
        result = contains([1], 2)
        self.assertFalse(result)

    def test_small_list_number_present(self):
        result = contains([2, 4, 6], 4)
        self.assertTrue(result)

    def test_small_list_number_absent(self):
        result = contains([2, 4, 6], 5)
        self.assertFalse(result)

    def test_large_list_number_present(self):
        result = contains([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 8)
        self.assertTrue(result)

    def test_large_list_number_absent(self):
        result = contains([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 0)
        self.assertFalse(result)

    def test_large_list_number_first(self):
        result = contains([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 1)
        self.assertTrue(result)

    def test_large_list_number_last(self):
        result = contains([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 10)
        self.assertTrue(result)


unittest.main(verbosity=2)