from intervals import merge


def test_unsorted_overlaps():
    assert merge([(5, 8), (1, 3), (2, 6)]) == [(1, 8)]


def test_contained():
    assert merge([(1, 10), (3, 4)]) == [(1, 10)]


def test_touching():
    assert merge([(1, 2), (2, 3)]) == [(1, 3)]


def test_disjoint_preserved():
    assert merge([(1, 2), (5, 6)]) == [(1, 2), (5, 6)]


def test_empty():
    assert merge([]) == []