text: import unittest
  
  from flatlib import const
  from flatlib.chart import Chart
  from flatlib.datetime import Datetime
  from flatlib.geopos import GeoPos
  
  
  class ChartTests(unittest.TestCase):
  
      def setUp(self):
          self.date = Datetime('2015/03/13', '17:00', '+00:00')
          self.pos = GeoPos('38n32', '8w54')
  
      def test_solar_return_hsys(self):
          """Solar return charts must maintain original house system."""
          chart = Chart(self.date, self.pos, hsys=const.HOUSES_MORINUS)
          sr_chart = chart.solarReturn(2018)
          self.assertEqual(chart.hsys, sr_chart.hsys)
  