code: def test_invalid_constructor_equilibrium_length_not_sympifyable(
      self,
      equilibrium_length,
  ):
      with pytest.raises(SympifyError):
          _ = LinearSpring(
              self.stiffness, self.pathway, equilibrium_length
          )
  
imports: import pytest
  from sympy import S, Matrix, Symbol, SympifyError, sqrt
  from sympy.physics.mechanics import ActuatorBase, Force, ForceActuator, KanesMethod, LinearDamper, LinearPathway, LinearSpring, Particle, PinJoint, Point, ReferenceFrame, RigidBody, TorqueActuator, Vector, dynamicsymbols
  from sympy.core.expr import Expr
label_desc: Use image node_id 7 for calling the TestLinearSpring obj's underlying member method code with example usage: obj.test_invalid_constructor_equilibrium_length_not_sympifyable(equilibrium_length) without return types