old_contents: from __future__ import division
  
  from sympy import sqrt, simplify
  from sympy.physics.optics import Medium
  from sympy.abc import epsilon, mu
  from sympy.physics.units import c, u0, e0, m, kg, s, A
  
  def test_medium():
      m1 = Medium('m1')
      assert m1.intrinsic_impedance == sqrt(u0/e0)
      assert m1.speed == 1/sqrt(e0*u0)
      assert m1.refractive_index == c*sqrt(e0*u0)
      assert m1.permittivity == e0
      assert m1.permeability == u0
      m2 = Medium('m2', epsilon, mu)
      assert m2.intrinsic_impedance == sqrt(mu/epsilon)
      assert m2.speed == 1/sqrt(epsilon*mu)
      assert m2.refractive_index == c*sqrt(epsilon*mu)
      assert m2.permittivity == epsilon
      assert m2.permeability == mu
      # Increasing electric permittivity and magnetic permeability
      # by small amount from its value in vacuum.
      m3 = Medium('m3', 9.0*10**(-12)*s**4*A**2/(m**3*kg), 1.45*10**(-6)*kg*m/(A**2*s**2))
      assert m3.refractive_index > m1.refractive_index
      assert m3 > m1
      # Decreasing electric permittivity and magnetic permeability
      # by small amount from its value in vacuum.
      m4 = Medium('m4', 7.0*10**(-12)*s**4*A**2/(m**3*kg), 1.15*10**(-6)*kg*m/(A**2*s**2))
      assert m4.refractive_index < m1.refractive_index
      assert m4 < m1
      m5 = Medium('m5', permittivity=710*10**(-12)*s**4*A**2/(m**3*kg), n=1.33)
      assert simplify(m5.intrinsic_impedance - 6.24845417765552*kg*m**2/(A**2*s**3)) == 0
      assert abs(m5.speed - 225407863.157895*m/s) < 1e-6*m/s
      assert simplify(m5.refractive_index - 1.33000000000000) == 0
      assert simplify(m5.permittivity - 7.1e-10*A**2*s**4/(kg*m**3)) == 0
      assert simplify(m5.permeability - 2.77206575232851e-8*kg*m/(A**2*s**2)) == 0
  
new_contents: from __future__ import division
  
  from sympy import sqrt, simplify
  from sympy.physics.optics import Medium
  from sympy.abc import epsilon, mu
  from sympy.physics.units import c, u0, e0, m, kg, s, A
  
  def test_medium():
      m1 = Medium('m1')
      assert m1.intrinsic_impedance == sqrt(u0/e0)
      assert m1.speed == 1/sqrt(e0*u0)
      assert m1.refractive_index == c*sqrt(e0*u0)
      assert m1.permittivity == e0
      assert m1.permeability == u0
      m2 = Medium('m2', epsilon, mu)
      assert m2.intrinsic_impedance == sqrt(mu/epsilon)
      assert m2.speed == 1/sqrt(epsilon*mu)
      assert m2.refractive_index == c*sqrt(epsilon*mu)
      assert m2.permittivity == epsilon
      assert m2.permeability == mu
      # Increasing electric permittivity and magnetic permeability
      # by small amount from its value in vacuum.
      m3 = Medium('m3', 9.0*10**(-12)*s**4*A**2/(m**3*kg), 1.45*10**(-6)*kg*m/(A**2*s**2))
      assert m3.refractive_index > m1.refractive_index
      assert m3 > m1
      # Decreasing electric permittivity and magnetic permeability
      # by small amount from its value in vacuum.
      m4 = Medium('m4', 7.0*10**(-12)*s**4*A**2/(m**3*kg), 1.15*10**(-6)*kg*m/(A**2*s**2))
      assert m4.refractive_index < m1.refractive_index
      assert m4 < m1
      m5 = Medium('m5', permittivity=710*10**(-12)*s**4*A**2/(m**3*kg), n=1.33)
      assert abs(m5.intrinsic_impedance - 6.24845417765552*kg*m**2/(A**2*s**3)) \
                  < 1e-12*kg*m**2/(A**2*s**3)
      assert abs(m5.speed - 225407863.157895*m/s) < 1e-6*m/s
      assert abs(m5.refractive_index - 1.33000000000000) < 1e-12
      assert abs(m5.permittivity - 7.1e-10*A**2*s**4/(kg*m**3)) \
                  < 1e-20*A**2*s**4/(kg*m**3)
      assert abs(m5.permeability - 2.77206575232851e-8*kg*m/(A**2*s**2)) \
                  < 1e-20*kg*m/(A**2*s**2)
  
subject: Fix a test in test_medium