Binary Search

Binary_Search.py

# Written in Python 3.51 by Kurtis Mackey (Developed Test First)
# Binary Search

import unittest

def binary_search(array, num):
    """Given a sorted array of numbers,
       return True of num is in the array
       using Binary Search.
    """
    if type(array) != type(list()):
        raise TypeError('Must be of type: List()')
    if array != sorted(array):
        raise ValueError('Must be a Sorted Array for Binary Search')
    
    mid = len(array)//2
    if array[mid] == num:
        return True
    else:
        if num > array[-1] or num < array[0]:
            return False
        elif num <= array[mid]:
            return binary_search(array[:mid], num)
        elif num > array[mid]:
            return binary_search(array[mid:], num)
        else:
            return False


# ================  TESTING ===================

class BinarySearchTest(unittest.TestCase):

    def test_binary_searchTrue(self):
        self.assertEqual(binary_search([1, 2, 3, 4, 5], 4), True)
        self.assertEqual(binary_search([4, 5, 6, 7, 8, 9], 4), True)
        self.assertEqual(binary_search([10, 20, 30, 40, 50], 50), True)
        self.assertEqual(binary_search([10, 100, 150, 300, 301], 150), True)
        self.assertEqual(binary_search([-1, 10, 100, 150, 300, 301], -1), True)
    
    def test_binary_searchFalse(self):
        self.assertEqual(binary_search([1, 2, 3, 4, 5], 10), False)
        self.assertEqual(binary_search([4, 5, 6, 7, 8, 9], 0), False)
        self.assertEqual(binary_search([10, 20, 30, 40, 50], 11), False)
        self.assertEqual(binary_search([10, 100, 150, 300, 301], 151), False)
        self.assertEqual(binary_search([10, 100, 150, 300, 301], -1), False)
        
    def test_binary_searchError(self):
        self.assertRaises(TypeError, binary_search, 1, 2)
        self.assertRaises(TypeError, binary_search, 'abcde', 'b')
        self.assertRaises(TypeError, binary_search, 'edcba', 'b')
        self.assertRaises(ValueError, binary_search, [3, 2, 1], 2)
        self.assertRaises(ValueError, binary_search, [4, 2, 1, 6, 1, 2], 15)


if __name__ == '__main__':
    unittest.main()