code: def test_2D_pathway_length(self):
      self.pB.set_pos(self.pA, 2 * self.q1 * self.N.x)
      expected = 2 * sqrt(self.q1**2)
      assert self.pathway.length == expected
  
imports: import pytest
  from sympy import Rational, Symbol, cos, pi, sin, sqrt
  from sympy.physics.mechanics import Force, LinearPathway, ObstacleSetPathway, PathwayBase, Point, ReferenceFrame, WrappingCylinder, WrappingGeometryBase, WrappingPathway, WrappingSphere, dynamicsymbols
  from sympy.simplify.simplify import simplify
label_desc: Use image node_id 11 for calling the TestLinearPathway obj's underlying member method code with example usage: obj.test_2D_pathway_length() without return types