def test_zero():
x = Symbol('x')
y = Symbol('y')
assert 0**x != 0
assert 0**(2 * x) == 0**x
assert 0**(1.0 * x) == 0**x
assert 0**(2.0 * x) == 0**x
assert (0**(2 - x)).as_base_exp() == (0, 2 - x)
assert 0**(x - 2) != S.Infinity**(2 - x)
assert 0**(2 * x * y) == 0**(x * y)
assert 0**(-2 * x * y) == S.ComplexInfinity**(x * y)
#Test issue 19572
assert 0**-oo is zoo
assert power(0, -oo) is zoo
def test_power_dispatcher():
class NewBase(Expr):
pass
class NewPow(NewBase, Pow):
pass
a, b = Symbol('a'), NewBase()
@power.register(Expr, NewBase)
@power.register(NewBase, Expr)
@power.register(NewBase, NewBase)
def _(a, b):
return NewPow(a, b)
# Pow called as fallback
assert power(2, 3) == 8*S.One
assert power(a, 2) == Pow(a, 2)
assert power(a, a) == Pow(a, a)
# NewPow called by dispatch
assert power(a, b) == NewPow(a, b)
assert power(b, a) == NewPow(b, a)
assert power(b, b) == NewPow(b, b)
