def test_evalf_sum():
assert Sum(n, (n, 1, 2)).evalf() == 3.
assert Sum(n, (n, 1, 2)).doit().evalf() == 3.
# the next test should return instantly
assert Sum(1 / n, (n, 1, 2)).evalf() == 1.5
# issue 8219
assert Sum(E / factorial(n), (n, 0, oo)).evalf() == (E * E).evalf()
# issue 8254
assert Sum(2**n * n / factorial(n),
(n, 0, oo)).evalf() == (2 * E * E).evalf()
# issue 8411
s = Sum(1 / x**2, (x, 100, oo))
assert s.n() == s.doit().n()
