def test_get_primary_sensors_by_period(self):
        w = Workflow('test')
        w.add_primary_sensor('avhrr.n10', (1986, 11, 17), (1991, 9, 16))
        w.add_primary_sensor('avhrr.n11', (1988, 11, 8), (1994, 12, 31))
        w.add_primary_sensor('avhrr.n12', (1991, 9, 16), (1998, 12, 14))
        w.add_secondary_sensor('avhrr.n10', (1986, 11, 17), (1991, 9, 16))
        w.add_secondary_sensor('avhrr.n11', (1988, 11, 8), (1994, 12, 31))
        w.add_secondary_sensor('avhrr.n12', (1991, 9, 16), (1998, 12, 14))

        sensors = w._get_primary_sensors_by_period()
        """:type : list"""
        self.assertEqual(2, len(sensors))
        sensor_1 = sensors[0]
        """:type : Sensor"""
        sensor_2 = sensors[1]
        """:type : Sensor"""
        self.assertEqual("avhrr.n11", sensor_1.get_name())
        self.assertEqual(Period('1988-11-08', '1991-09-16'), sensor_1.get_period())
        self.assertEqual("avhrr.n12", sensor_2.get_name())
        self.assertEqual(Period('1991-09-16', '1994-12-31'), sensor_2.get_period())
    def test_get_primary_sensors_by_period(self):
        w = Workflow('test')
        w.add_primary_sensor('avhrr.n10', (1986, 11, 17), (1991, 9, 16))
        w.add_primary_sensor('avhrr.n11', (1988, 11, 8), (1994, 12, 31))
        w.add_primary_sensor('avhrr.n12', (1991, 9, 16), (1998, 12, 14))
        w.add_secondary_sensor('avhrr.n10', (1986, 11, 17), (1991, 9, 16))
        w.add_secondary_sensor('avhrr.n11', (1988, 11, 8), (1994, 12, 31))
        w.add_secondary_sensor('avhrr.n12', (1991, 9, 16), (1998, 12, 14))

        sensors = w._get_primary_sensors_by_period()
        """:type : list"""
        self.assertEqual(2, len(sensors))
        sensor_1 = sensors[0]
        """:type : Sensor"""
        sensor_2 = sensors[1]
        """:type : Sensor"""
        self.assertEqual("avhrr.n11", sensor_1.get_name())
        self.assertEqual(Period('1988-11-08', '1991-09-16'),
                         sensor_1.get_period())
        self.assertEqual("avhrr.n12", sensor_2.get_name())
        self.assertEqual(Period('1991-09-16', '1994-12-31'),
                         sensor_2.get_period())