Test radical on a field without squarefree_decomposition()

Author: user202729

src/sage/rings/polynomial/polynomial_element.pyx

@@ -10534,6 +10534,8 @@ cdef class Polynomial(CommutativePolynomial):
             Traceback (most recent call last):
             ...
             NotImplementedError: square-free decomposition not implemented for this polynomial
+            sage: f.radical()
+            y^2 + ((x^2 + x + 1)/(x + 1))*y + x/(x + 1)
         """
         P = self._parent
         R = P.base_ring()