def test_lazy_constant():
import time
def target():
time.sleep(1)
return 12345
with pf.Graph() as graph:
value = pf.lazy_constant(target)
start = time.time()
assert graph(value) == 12345
assert time.time() - start > 1
start = time.time()
assert graph(value) == 12345
assert time.time() - start < 0.01
def test_lazy_constant_not_callable():
with pytest.raises(ValueError):
with pf.Graph() as graph:
pf.lazy_constant(None)
