code: def test_matrix_to_vector():
      m = Matrix([[1], [2], [3]])
      assert matrix_to_vector(m, C) == C.i + 2 * C.j + 3 * C.k
      m = Matrix([[0], [0], [0]])
      assert (
          matrix_to_vector(m, N)
          == matrix_to_vector(m, C)
          == Vector.zero
      )
      m = Matrix([[q1], [q2], [q3]])
      assert matrix_to_vector(m, N) == q1 * N.i + q2 * N.j + q3 * N.k
  
file_path: sympy/sympy/vector/tests/test_functions.py
imports: from sympy.vector.vector import Vector
  from sympy.vector.coordsysrect import CoordSys3D
  from sympy.vector.functions import express, matrix_to_vector, orthogonalize
  from sympy.core.numbers import Rational
  from sympy.core.singleton import S
  from sympy.core.symbol import symbols
  from sympy.functions.elementary.miscellaneous import sqrt
  from sympy.functions.elementary.trigonometric import cos, sin
  from sympy.matrices.immutable import ImmutableDenseMatrix
  from sympy.testing.pytest import raises
label_desc: Use image node_id 2 for calling a global function with example usage: test_matrix_to_vector() without return types