def test_merge_few_uniques():
arr = [5, 12, 7, 5, 5, 7]
expected = [5, 5, 5, 7, 7, 12]
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_nearly_sorted():
arr = [2, 3, 5, 7, 13, 11]
expected = [2, 3, 5, 7, 11, 13]
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_reverse_sorted():
arr = [20, 18, 12, 8, 5, -2]
expected = [-2, 5, 8, 12, 18, 20]
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_sort_case1():
arr = [8, 5, 13, 9, 90]
expected = [5, 8, 9, 13, 90]
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_sorted_arr():
arr = [15, 17, 18, 20, 21, 25]
expected = [15, 17, 18, 20, 21, 25]
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_empty_arr():
arr = []
expected = []
merge_sort(arr)
actual = arr
assert actual == expected
def test_merge_one_element():
arr = [13]
expected = [13]
merge_sort(arr)
actual = arr
assert actual == expected