old_contents: """Tests for functions that calculate plasma parameters using cython."""
  
  import numpy as np
  import pytest
  from astropy import units as u
  from warnings import simplefilter
  
  from ...utils.exceptions import RelativityWarning, RelativityError
  from ...utils.exceptions import PhysicsError
  from ...constants import c, m_p, m_e, e, mu0
  
  from ..parameters_cython import (thermal_speed,
                                   )
      
  def test_thermal_speed():
      r"""Test for cythonized version of thermal_speed()."""
      trueVal = 593083.619464999
      T = 11604
      methodVal = thermal_speed(T, particle="e", method="most_probable")
      testTrue = np.isclose(methodVal,
                            trueVal,
                            rtol=0.0,
                            atol=1e-16)
      exceptStr = f'Thermal speed value is {methodVal}, should be {trueVal}.'
      assert testTrue, exceptStr
new_contents: """Tests for functions that calculate plasma parameters using cython."""
  
  import numpy as np
  import pytest
  from astropy import units as u
  from warnings import simplefilter
  
  from plasmapy.utils.exceptions import RelativityWarning, RelativityError
  from plasmapy.utils.exceptions import PhysicsError
  from plasmapy.constants import c, m_p, m_e, e, mu0
  
  from plasmapy.physics.parameters_cython import (thermal_speed,
                                   )
  def test_thermal_speed():
      r"""Test for cythonized version of thermal_speed()."""
      trueVal = 593083.619464999
      T = 11604
      methodVal = thermal_speed(T, particle="e", method="most_probable")
      testTrue = np.isclose(methodVal,
                            trueVal,
                            rtol=0.0,
                            atol=1e-16)
      exceptStr = f'Thermal speed value is {methodVal}, should be {trueVal}.'
      assert testTrue, exceptStr
subject: Update tests for cython parameters