Add a test

Author: kwankyu

src/sage/rings/function_field/jacobian_base.py

@@ -654,6 +654,27 @@ def __call__(self, x):
             True
             sage: J_hess(q) == p
             True
+
+        If ``x`` is an effective divisor, it is checked that the degree
+        is equal to the degree of the base divisor. See :issue:38623.
+
+            sage: K.<x> = FunctionField(GF(7))
+            sage: _.<t> = K[]
+            sage: F.<y> = K.extension(t^2 - x^6 - 3)
+            sage: O = F.maximal_order()
+            sage: D1 = (O.ideal(x + 1, y + 2)*O.ideal(x + 2, y + 2)).divisor()
+            sage: I = O.ideal(x + 3, y+5)*O.ideal(x + 4, y + 5)*O.ideal(x + 5, y + 5)
+            sage: D2 = I.divisor()
+            sage: J = F.jacobian(model='hess')
+            sage: J(D1)
+            [Place (x + 1, y + 2)
+             + Place (x + 2, y + 2)]
+            sage: J(D2)
+            Traceback (most recent call last):
+            ...
+            ValueError: effective divisor is not of degree 2
+            sage: J.base_divisor().degree()
+            2
         """
         F = self._function_field
         if isinstance(x, JacobianPoint_base):