import random
from sort import MergeSort
sort = MergeSort()
def test_sorting():
'''
Testing sort method.
'''
assert sort([]) == []
assert sort([1]) == [1]
assert sort([0, 1]) == [0, 1]
assert sort([1, 0]) == [0, 1]
n = 1000
input = range(n)
random.shuffle(input)
assert sort(input) == range(n)
def test_basic_inversions():
'''
Testing basic cases of inversion counting.
'''
assert sort([]) == []
assert sort.inversions == 0, "for empty input"
assert sort([1]) == [1]
