def test_add_change_works_on_top_of_existing_colour_definition():
rl = RunLengthList([(0, 'foo'), (2, +20)])
rl.add_change(2, -20) #deliberately try and get it to the left
assert rl.items() == [(0, 'foo'), (2, -20)]
def test_RunLengthList_add_change_already_got_index():
c = RunLengthList([(0, 'foo'), (3, 'bar')])
c.add_change(3, 'baz')
assert c.items() == [(0, 'foo'), (3, 'baz')]
def test_RunLengthList_add_change_normalises_afterwards():
r = RunLengthList([(0, 'foo')])
r.add_change(2, 'foo')
r.add_change(1, 'bar')
assert r.items() == [(0, 'foo'), (1, 'bar')]
def test_RunLengthList_add_change():
c = RunLengthList([(0, 1), (3, 2)])
c.add_change(1, 3)
assert c.items() == [(0, 1), (1, 3), (3, 2)]
