new_contents: import unittest
  import turbopump
  
  class TestStringMethods(unittest.TestCase):
  
      def test_m_dot2gpm(self):
          # 100 kg s**-1, 1000 kg m**-3 --> 1584 gal min**-1
          self.assertAlmostEqual(1584, turbopump.m_dot2gpm(100, 1000), delta=2)
  
  
      def test_gpm_m_dot_inverse(self):
          for m_dot in [1, 100, 1000, 2434]:
              for rho in [1, 100, 1000, 2000]:
                  self.assertAlmostEqual(m_dot, turbopump.gpm2m_dot(
                      turbopump.m_dot2gpm(m_dot, rho), rho))
  
  
      def test_rpm_radsec_inverse(self):
          for rpm in [1, 1e3, 1e6]:
              self.assertAlmostEqual(rpm, turbopump.radsec2rpm(
                  turbopump.rpm2radsec(rpm)))
  
      def test_sample61(self):
          # Check against sample problem 6-1 from Huzel and Huang.
          rho_ox = 1143 # 71.38 lbm ft**-3
          rho_fuel = 808.1 # 50.45 lbm ft**-3
          dp_ox = 9.997e6 # 1450 psi
          dp_fuel = 11.55e6 # 1675 psi
          m_dot_ox = 894 # 1971 lbm s**-1
          m_dot_fuel = 405 # 892 lbm s**-1
          N = turbopump.rpm2radsec(7000)
  
          # Check speed
          self.assertAlmostEqual(7000, turbopump.radsec2rpm(N))
  
          # Check pump head
          self.assertAlmostEqual(2930, turbopump.dp2head(dp_ox, rho_ox), delta=10)
          self.assertAlmostEqual(4790, turbopump.dp2head(dp_fuel, rho_fuel), delta=10)
  
          # Check volume flow rate
          self.assertAlmostEqual(12420, turbopump.m_dot2gpm(m_dot_ox, rho_ox), delta=40)
          self.assertAlmostEqual(7960, turbopump.m_dot2gpm(m_dot_fuel, rho_fuel), delta=20)
  
          # Check specific speed
          self.assertAlmostEqual(1980, turbopump.pump_specific_speed_us(
              dp_ox, m_dot_ox, rho_ox, N),
              delta=30)
          self.assertAlmostEqual(1083, turbopump.pump_specific_speed_us(
              dp_fuel, m_dot_fuel, rho_fuel, N),
              delta=20)
  
  
  if __name__ == '__main__':
      unittest.main()
subject: Add unit tests for turbopump.