code: def test_valid_constructor(
      self,
      stiffness,
      expected_stiffness,
      equilibrium_length,
      expected_equilibrium_length,
      force,
  ):
      self.pB.set_pos(self.pA, self.q * self.N.x)
      spring = LinearSpring(stiffness, self.pathway, equilibrium_length)
  
      assert isinstance(spring, LinearSpring)
  
      assert hasattr(spring, "stiffness")
      assert isinstance(spring.stiffness, ExprType)
      assert spring.stiffness == expected_stiffness
  
      assert hasattr(spring, "pathway")
      assert isinstance(spring.pathway, LinearPathway)
      assert spring.pathway == self.pathway
  
      assert hasattr(spring, "equilibrium_length")
      assert isinstance(spring.equilibrium_length, ExprType)
      assert spring.equilibrium_length == expected_equilibrium_length
  
      assert hasattr(spring, "force")
      assert isinstance(spring.force, ExprType)
      assert spring.force == force
  
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 4 for calling the TestLinearSpring obj's underlying member method code with example usage: obj.test_valid_constructor(stiffness, expected_stiffness, equilibrium_length, expected_equilibrium_length, force) without return types