def test_none_as_literal():
def f(x):
return x is None
g = guard(None)(f)
with pytest.raises(NoMatch):
g(True)
assert g(None)
def test_literal_type_is_treated_as_object():
def f(obj, int_type):
return int_type(obj)
g = guard(Any, int)(f)
with pytest.raises(NoMatch):
g('1234', float)
assert g('1234', int) == 1234
def test_has_attribute_predicate():
def f(x):
return x.count(2)
g = guard(Any.has('count'))(f)
with pytest.raises(NoMatch):
g({})
with pytest.raises(NoMatch):
g(1)
assert g((1, 2, 2, 3)) == 2
def test_literal_integer_predicate():
def f(x):
return 2 * x
g = guard(4)(f)
with pytest.raises(NoMatch):
g('Something')
with pytest.raises(NoMatch):
g(3)
assert g(4) == 8
def test_literal_string_predicate():
def fn(a):
return a + ' string'
g = guard('this is a')(fn)
with pytest.raises(NoMatch):
g(0)
with pytest.raises(NoMatch):
g('')
assert g('this is a') == 'this is a string'
def test_with_regex_matching():
def f(s):
return s
g = guard(Any.re('A|B'))(f)
with pytest.raises(NoMatch):
g('Cat')
with pytest.raises(NoMatch):
g('CAT')
assert g('About') == 'About'
def test_type_predicate():
def f(a, b):
return a * b
g = guard(Any(str), Any(int))(f)
with pytest.raises(NoMatch):
g('eee', 'k')
with pytest.raises(NoMatch):
g(3, 2)
with pytest.raises(NoMatch):
g('eeeeeeeeee', None)
assert g('eeky', 3) == 'eekyeekyeeky'
def test_literal_object_predicate():
o = object()
def f(x):
return True
g = guard(o)(f)
with pytest.raises(NoMatch):
g(0)
with pytest.raises(NoMatch):
g(object)
assert g(o)
def test_check_varargs():
def count_args(*args):
return len(args)
g = guard(1, Any.args(Any(int)))(count_args)
with pytest.raises(NoMatch):
g(0)
with pytest.raises(NoMatch):
g(1, 'a')
with pytest.raises(NoMatch):
g(1, *(['a'] * 20))
assert g(1, 2, 3) == 3
assert g(*([1] * 20)) == 20
def test_has_with_predicate():
X = type('X', (object, ), {'value': None})
def f(x):
return x.value
g = guard(Any.has(value=Any(int)))(f)
with pytest.raises(NoMatch):
g('123')
with pytest.raises(NoMatch):
x = X()
x.value = '321'
g(x)
x = X()
x.value = 321
assert g(x) == 321
def test_any_argument(one_arg_fn):
fn = guard(Any)(one_arg_fn)
assert fn(3) == 4
assert fn(2) == 3
def test_run_function_if_predicate_function(one_arg_fn):
fn = guard(lambda x: x == 2)(one_arg_fn)
with pytest.raises(NoMatch):
fn(3)
assert fn(2) == 3
def test_any_with_no_types():
def f(x):
return x
g = guard(Any())(f)
assert g(3) == 3
def test_return_decorator(zero_arg_fn):
result = guard()(zero_arg_fn)
assert callable(result)
invoke_result = result()
assert invoke_result == 'Test'