def test_battery_and_light(self):
l = LightMeter(incident_light=4096, battery=1.44)
assert l.reading() == 4096
def test_no_battery(self):
l = LightMeter(incident_light=0, battery=1.44)
assert l.reading() == 0
def test_no_light(self):
l = LightMeter(incident_light=4096, battery=0)
assert l.reading() == None
def test_no_battery_no_light(self):
l = LightMeter()
assert l.reading() == None