def test_finds_at_end(self):
'''
Finds a key at the end of an array
'''
arr = [1, 2, 5, 7, 9, 10]
assert binarysearch(arr, 10, 0, len(arr) - 1) == 5
def test_first_returned(self):
'''
Returns the first index if many keys are found.
'''
arr = [1, 2, 3, 4, 4, 4, 4, 4, 6]
assert binarysearch(arr, 4, 0, len(arr) - 1) == 3
def test_many_exists(self):
'''
Should find a key in a small array
'''
arr = [1, 2, 5, 6, 7, 10, 20, 22, 24, 26, 26, 28]
assert binarysearch(arr, 20, 0, len(arr) - 1) == 6
def test_single_not_exists(self):
'''
Should not find a key in a len==1 array if it does not exist.
'''
arr = [2]
assert binarysearch(arr, 1, 0, len(arr) - 1) == -1
def test_single_exists(self):
'''
Should find a single key in an array
'''
arr = [1]
assert binarysearch(arr, 1, 0, len(arr) - 1) == 0
def test_empty(self):
'''
No key should be found in an empty array
'''
arr = []
assert binarysearch(arr, 1, 0, len(arr) - 1) == -1
def test_many_not_exists(self):
'''
Shows there is no key if it doesn't exist
'''
arr = [1, 2, 3, 5, 7, 8, 10, 13, 15, 16, 17, 20, 22, 24, 25]
assert binarysearch(arr, 4, 0, len(arr) - 1) == -1