def test_obslist_s2n_zeroweight():
rng = np.random.RandomState(seed=11)
obslist = ObsList()
for _ in range(3):
obs = Observation(
image=rng.normal(size=(13, 15)),
weight=np.zeros((13, 15)),
store_pixels=False,
)
obslist.append(obs)
assert np.allclose(obslist.get_s2n(), -9999)
def test_obslist_s2n():
rng = np.random.RandomState(seed=11)
obslist = ObsList()
numer = 0
denom = 0
for _ in range(3):
obs = Observation(image=rng.normal(size=(13, 15)))
numer += np.sum(obs.image)
denom += np.sum(1.0 / obs.weight)
obslist.append(obs)
s2n = obslist.get_s2n()
assert s2n == numer / np.sqrt(denom)