Test RangeStream

[lmmx]

• [x] Test empty_range_stream.isempty() is True on the empty range response

• [x] empty_range_stream.spanning_range == Range(0,0)

• [ ] Multiple range span with two:

s = make_range_stream(0, 4)
s.handle_byte_range(6,11)
s.spanning_range == Range(0,11)

better yet, parameterize range_pairs over [[(0,4), (6,11)], [(2,3), (5,6), (8,9)]]:

s = make_range_stream(0, 4)
for start, stop in range_pairs:
    s.handle_byte_range(start, stop)
rng_min, rng_max = range_pairs[0][0], range_pairs[-1][-1]
s.spanning_range == Range(rng_min,rng_max)

[lmmx]

Closed with 82050bb70756d11cac00c34d08cb47bcd50a7134