import git_time_tracker

def test_year_ranges_1():
    assert git_time_tracker.fmt_year_ranges([1,2,3]) == '1-3'

def test_year_ranges_2():
    assert git_time_tracker.fmt_year_ranges([1,3]) == '1,3'

def test_year_ranges_3():
    assert git_time_tracker.fmt_year_ranges([1,2,4]) == '1-2,4'

def test_year_ranges_4():
    assert git_time_tracker.fmt_year_ranges([1,2,4,5]) == '1-2,4-5'