code: def test_chebyshevt_poly():
      raises(ValueError, lambda: chebyshevt_poly(-1, x))
  
      assert chebyshevt_poly(1, x, polys=True) == Poly(x)
  
      assert chebyshevt_poly(0, x) == 1
      assert chebyshevt_poly(1, x) == x
      assert chebyshevt_poly(2, x) == 2 * x**2 - 1
      assert chebyshevt_poly(3, x) == 4 * x**3 - 3 * x
      assert chebyshevt_poly(4, x) == 8 * x**4 - 8 * x**2 + 1
      assert chebyshevt_poly(5, x) == 16 * x**5 - 20 * x**3 + 5 * x
      assert (
          chebyshevt_poly(6, x)
          == 32 * x**6 - 48 * x**4 + 18 * x**2 - 1
      )
  
      assert chebyshevt_poly(1).dummy_eq(x)
      assert chebyshevt_poly(1, polys=True) == Poly(x)
  
file_path: sympy/sympy/polys/tests/test_orthopolys.py
imports: from sympy.core.numbers import Rational
  from sympy.core.singleton import S
  from sympy.core.symbol import symbols
  from sympy.polys.polytools import Poly
  from sympy.testing.pytest import raises
  from sympy.polys.orthopolys import jacobi_poly, gegenbauer_poly, chebyshevt_poly, chebyshevu_poly, hermite_poly, hermite_prob_poly, legendre_poly, laguerre_poly, spherical_bessel_fn
  from sympy.abc import x, a, b
label_desc: Use image node_id 3 for calling a global function with example usage: test_chebyshevt_poly() without return types