def test_error_raised_when_no_intersection(self):
fb1 = FrequencyBand(0, 100)
fb2 = FrequencyBand(200, 500)
self.assertRaises(ValueError, lambda: fb1.intersect(fb2))
def test_can_intersect(self):
fb1 = FrequencyBand(0, 100)
fb2 = FrequencyBand(50, 150)
intersection = fb1.intersect(fb2)
self.assertEqual(FrequencyBand(50, 100), intersection)