code: def test_conversion():
      L = QQ.old_poly_ring(x, y, order="ilex")
      G = QQ.old_poly_ring(x, y)
  
      assert L.convert(x) == L.convert(G.convert(x), G)
      assert G.convert(x) == G.convert(L.convert(x), L)
      raises(
          CoercionFailed, lambda: G.convert(L.convert(1 / (1 + x)), L)
      )
  
file_path: sympy/sympy/polys/domains/tests/test_polynomialring.py
imports: from sympy.polys.domains import QQ, ZZ
  from sympy.polys.polyerrors import ExactQuotientFailed, CoercionFailed, NotReversible
  from sympy.abc import x, y
  from sympy.testing.pytest import raises
label_desc: Use image node_id 4 for calling a global function with example usage: test_conversion() without return types