"""Unit tests for the positional only argument syntax specified in PEP 570."""
import dis
import pickle
import unittest
from test.support import check_syntax_error
def global_pos_only_f(a, b, /):
return a, b
def global_pos_only_and_normal(a, /, b):
return a, b
def global_pos_only_defaults(a=1, /, b=2):
return a, b
class PositionalOnlyTestCase(unittest.TestCase):
def assertRaisesSyntaxError(self, codestr, regex="invalid syntax"):
with self.assertRaisesRegex(SyntaxError, regex):
compile(codestr + "\n", "<test>", "single")
def test_invalid_syntax_errors(self):
check_syntax_error(self, "def f(a, b = 5, /, c): pass", "non-default argument follows default argument")
check_syntax_error(self, "def f(a = 5, b, /, c): pass", "non-default argument follows default argument")
check_syntax_error(self, "def f(a = 5, b=1, /, c, *, d=2): pass", "non-default argument follows default argument")
check_syntax_error(self, "def f(a = 5, b, /): pass", "non-default argument follows default argument")
check_syntax_error(self, "def f(*args, /): pass")
check_syntax_error(self, "def f(*args, a, /): pass")
check_syntax_error(self, "def f(**kwargs, /): pass")
check_syntax_error(self, "def f(/, a = 1): pass")
check_syntax_error(self, "def f(/, a): pass")
check_syntax_error(self, "def f(/): pass")
check_syntax_error(self, "def f(*, a, /): pass")
check_syntax_error(self, "def f(*, /, a): pass")
check_syntax_error(self, "def f(a, /, a): pass", "duplicate argument 'a' in function definition")
check_syntax_error(self, "def f(a, /, *, a): pass", "duplicate argument 'a' in function definition")
check_syntax_error(self, "def f(a, b/2, c): pass")
check_syntax_error(self, "def f(a, /, c, /): pass")
check_syntax_error(self, "def f(a, /, c, /, d): pass")
check_syntax_error(self, "def f(a, /, c, /, d, *, e): pass")
check_syntax_error(self, "def f(a, *, c, /, d, e): pass")
def test_invalid_syntax_errors_async(self):
check_syntax_error(self, "async def f(a, b = 5, /, c): pass", "non-default argument follows default argument")
check_syntax_error(self, "async def f(a = 5, b, /, c): pass", "non-default argument follows default argument")
check_syntax_error(self, "async def f(a = 5, b=1, /, c, d=2): pass", "non-default argument follows default argument")
check_syntax_error(self, "async def f(a = 5, b, /): pass", "non-default argument follows default argument")
check_syntax_error(self, "async def f(*args, /): pass")
check_syntax_error(self, "async def f(*args, a, /): pass")
check_syntax_error(self, "async def f(**kwargs, /): pass")
check_syntax_error(self, "async def f(/, a = 1): pass")
check_syntax_error(self, "async def f(/, a): pass")
check_syntax_error(self, "async def f(/): pass")
check_syntax_error(self, "async def f(*, a, /): pass")
check_syntax_error(self, "async def f(*, /, a): pass")
check_syntax_error(self, "async def f(a, /, a): pass", "duplicate argument 'a' in function definition")
check_syntax_error(self, "async def f(a, /, *, a): pass", "duplicate argument 'a' in function definition")
check_syntax_error(self, "async def f(a, b/2, c): pass")
check_syntax_error(self, "async def f(a, /, c, /): pass")
check_syntax_error(self, "async def f(a, /, c, /, d): pass")
check_syntax_error(self, "async def f(a, /, c, /, d, *, e): pass")
check_syntax_error(self, "async def f(a, *, c, /, d, e): pass")
def test_optional_positional_only_args(self):
def f(a, b=10, /, c=100):
return a + b + c
self.assertEqual(f(1, 2, 3), 6)
self.assertEqual(f(1, 2, c=3), 6)
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'b'"):
f(1, b=2, c=3)
self.assertEqual(f(1, 2), 103)
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'b'"):
f(1, b=2)
self.assertEqual(f(1, c=2), 13)
def f(a=1, b=10, /, c=100):
return a + b + c
self.assertEqual(f(1, 2, 3), 6)
self.assertEqual(f(1, 2, c=3), 6)
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'b'"):
f(1, b=2, c=3)
self.assertEqual(f(1, 2), 103)
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'b'"):
f(1, b=2)
self.assertEqual(f(1, c=2), 13)
def test_syntax_for_many_positional_only(self):
# more than 255 positional only arguments, should compile ok
fundef = "def f(%s, /):\n pass\n" % ', '.join('i%d' % i for i in range(300))
compile(fundef, "<test>", "single")
def test_pos_only_definition(self):
def f(a, b, c, /, d, e=1, *, f, g=2):
pass
self.assertEqual(5, f.__code__.co_argcount) # 3 posonly + 2 "standard args"
self.assertEqual(3, f.__code__.co_posonlyargcount)
self.assertEqual((1,), f.__defaults__)
def f(a, b, c=1, /, d=2, e=3, *, f, g=4):
pass
self.assertEqual(5, f.__code__.co_argcount) # 3 posonly + 2 "standard args"
self.assertEqual(3, f.__code__.co_posonlyargcount)
self.assertEqual((1, 2, 3), f.__defaults__)
def test_pos_only_call_via_unpacking(self):
def f(a, b, /):
return a + b
self.assertEqual(f(*[1, 2]), 3)
def test_use_positional_as_keyword(self):
def f(a, /):
pass
expected = r"f\(\) got some positional-only arguments passed as keyword arguments: 'a'"
with self.assertRaisesRegex(TypeError, expected):
f(a=1)
def f(a, /, b):
pass
expected = r"f\(\) got some positional-only arguments passed as keyword arguments: 'a'"
with self.assertRaisesRegex(TypeError, expected):
f(a=1, b=2)
def f(a, b, /):
pass
expected = r"f\(\) got some positional-only arguments passed as keyword arguments: 'a, b'"
with self.assertRaisesRegex(TypeError, expected):
f(a=1, b=2)
def test_positional_only_and_arg_invalid_calls(self):
def f(a, b, /, c):
pass
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'c'"):
f(1, 2)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 2 required positional arguments: 'b' and 'c'"):
f(1)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 3 required positional arguments: 'a', 'b', and 'c'"):
f()
with self.assertRaisesRegex(TypeError, r"f\(\) takes 3 positional arguments but 4 were given"):
f(1, 2, 3, 4)
def test_positional_only_and_optional_arg_invalid_calls(self):
def f(a, b, /, c=3):
pass
f(1, 2) # does not raise
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'b'"):
f(1)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 2 required positional arguments: 'a' and 'b'"):
f()
with self.assertRaisesRegex(TypeError, r"f\(\) takes from 2 to 3 positional arguments but 4 were given"):
f(1, 2, 3, 4)
def test_positional_only_and_kwonlyargs_invalid_calls(self):
def f(a, b, /, c, *, d, e):
pass
f(1, 2, 3, d=1, e=2) # does not raise
with self.assertRaisesRegex(TypeError, r"missing 1 required keyword-only argument: 'd'"):
f(1, 2, 3, e=2)
with self.assertRaisesRegex(TypeError, r"missing 2 required keyword-only arguments: 'd' and 'e'"):
f(1, 2, 3)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'c'"):
f(1, 2)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 2 required positional arguments: 'b' and 'c'"):
f(1)
with self.assertRaisesRegex(TypeError, r" missing 3 required positional arguments: 'a', 'b', and 'c'"):
f()
with self.assertRaisesRegex(TypeError, r"f\(\) takes 3 positional arguments but 6 positional arguments "
r"\(and 2 keyword-only arguments\) were given"):
f(1, 2, 3, 4, 5, 6, d=7, e=8)
with self.assertRaisesRegex(TypeError, r"f\(\) got an unexpected keyword argument 'f'"):
f(1, 2, 3, d=1, e=4, f=56)
def test_positional_only_invalid_calls(self):
def f(a, b, /):
pass
f(1, 2) # does not raise
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'b'"):
f(1)
with self.assertRaisesRegex(TypeError, r"f\(\) missing 2 required positional arguments: 'a' and 'b'"):
f()
with self.assertRaisesRegex(TypeError, r"f\(\) takes 2 positional arguments but 3 were given"):
f(1, 2, 3)
def test_positional_only_with_optional_invalid_calls(self):
def f(a, b=2, /):
pass
f(1) # does not raise
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'a'"):
f()
with self.assertRaisesRegex(TypeError, r"f\(\) takes from 1 to 2 positional arguments but 3 were given"):
f(1, 2, 3)
def test_no_standard_args_usage(self):
def f(a, b, /, *, c):
pass
f(1, 2, c=3)
with self.assertRaises(TypeError):
f(1, b=2, c=3)
def test_change_default_pos_only(self):
def f(a, b=2, /, c=3):
return a + b + c
self.assertEqual((2,3), f.__defaults__)
f.__defaults__ = (1, 2, 3)
self.assertEqual(f(1, 2, 3), 6)
def test_lambdas(self):
x = lambda a, /, b: a + b
self.assertEqual(x(1,2), 3)
self.assertEqual(x(1,b=2), 3)
x = lambda a, /, b=2: a + b
self.assertEqual(x(1), 3)
x = lambda a, b, /: a + b
self.assertEqual(x(1, 2), 3)
x = lambda a, b, /, : a + b
self.assertEqual(x(1, 2), 3)
def test_invalid_syntax_lambda(self):
check_syntax_error(self, "lambda a, b = 5, /, c: None", "non-default argument follows default argument")
check_syntax_error(self, "lambda a = 5, b, /, c: None", "non-default argument follows default argument")
check_syntax_error(self, "lambda a = 5, b, /: None", "non-default argument follows default argument")
check_syntax_error(self, "lambda *args, /: None")
check_syntax_error(self, "lambda *args, a, /: None")
check_syntax_error(self, "lambda **kwargs, /: None")
check_syntax_error(self, "lambda /, a = 1: None")
check_syntax_error(self, "lambda /, a: None")
check_syntax_error(self, "lambda /: None")
check_syntax_error(self, "lambda *, a, /: None")
check_syntax_error(self, "lambda *, /, a: None")
check_syntax_error(self, "lambda a, /, a: None", "duplicate argument 'a' in function definition")
check_syntax_error(self, "lambda a, /, *, a: None", "duplicate argument 'a' in function definition")
check_syntax_error(self, "lambda a, /, b, /: None")
check_syntax_error(self, "lambda a, /, b, /, c: None")
check_syntax_error(self, "lambda a, /, b, /, c, *, d: None")
check_syntax_error(self, "lambda a, *, b, /, c: None")
def test_posonly_methods(self):
class Example:
def f(self, a, b, /):
return a, b
self.assertEqual(Example().f(1, 2), (1, 2))
self.assertEqual(Example.f(Example(), 1, 2), (1, 2))
self.assertRaises(TypeError, Example.f, 1, 2)
expected = r"f\(\) got some positional-only arguments passed as keyword arguments: 'b'"
with self.assertRaisesRegex(TypeError, expected):
Example().f(1, b=2)
def test_module_function(self):
with self.assertRaisesRegex(TypeError, r"f\(\) missing 2 required positional arguments: 'a' and 'b'"):
global_pos_only_f()
def test_closures(self):
def f(x,y):
def g(x2,/,y2):
return x + y + x2 + y2
return g
self.assertEqual(f(1,2)(3,4), 10)
with self.assertRaisesRegex(TypeError, r"g\(\) missing 1 required positional argument: 'y2'"):
f(1,2)(3)
with self.assertRaisesRegex(TypeError, r"g\(\) takes 2 positional arguments but 3 were given"):
f(1,2)(3,4,5)
def f(x,/,y):
def g(x2,y2):
return x + y + x2 + y2
return g
self.assertEqual(f(1,2)(3,4), 10)
def f(x,/,y):
def g(x2,/,y2):
return x + y + x2 + y2
return g
self.assertEqual(f(1,2)(3,4), 10)
with self.assertRaisesRegex(TypeError, r"g\(\) missing 1 required positional argument: 'y2'"):
f(1,2)(3)
with self.assertRaisesRegex(TypeError, r"g\(\) takes 2 positional arguments but 3 were given"):
f(1,2)(3,4,5)
def test_annotations_in_closures(self):
def inner_has_pos_only():
def f(x: int, /): ...
return f
assert inner_has_pos_only().__annotations__ == {'x': int}
class Something:
def method(self):
def f(x: int, /): ...
return f
assert Something().method().__annotations__ == {'x': int}
def multiple_levels():
def inner_has_pos_only():
def f(x: int, /): ...
return f
return inner_has_pos_only()
assert multiple_levels().__annotations__ == {'x': int}
def test_same_keyword_as_positional_with_kwargs(self):
def f(something,/,**kwargs):
return (something, kwargs)
self.assertEqual(f(42, something=42), (42, {'something': 42}))
with self.assertRaisesRegex(TypeError, r"f\(\) missing 1 required positional argument: 'something'"):
f(something=42)
self.assertEqual(f(42), (42, {}))
def test_mangling(self):
class X:
def f(self, __a=42, /):
return __a
def f2(self, __a=42, /, __b=43):
return (__a, __b)
def f3(self, __a=42, /, __b=43, *, __c=44):
return (__a, __b, __c)
self.assertEqual(X().f(), 42)
self.assertEqual(X().f2(), (42, 43))
self.assertEqual(X().f3(), (42, 43, 44))
def test_too_many_arguments(self):
# more than 255 positional-only arguments, should compile ok
fundef = "def f(%s, /):\n pass\n" % ', '.join('i%d' % i for i in range(300))
compile(fundef, "<test>", "single")
def test_serialization(self):
pickled_posonly = pickle.dumps(global_pos_only_f)
pickled_optional = pickle.dumps(global_pos_only_and_normal)
pickled_defaults = pickle.dumps(global_pos_only_defaults)
unpickled_posonly = pickle.loads(pickled_posonly)
unpickled_optional = pickle.loads(pickled_optional)
unpickled_defaults = pickle.loads(pickled_defaults)
self.assertEqual(unpickled_posonly(1,2), (1,2))
expected = r"global_pos_only_f\(\) got some positional-only arguments "\
r"passed as keyword arguments: 'a, b'"
with self.assertRaisesRegex(TypeError, expected):
unpickled_posonly(a=1,b=2)
self.assertEqual(unpickled_optional(1,2), (1,2))
expected = r"global_pos_only_and_normal\(\) got some positional-only arguments "\
r"passed as keyword arguments: 'a'"
with self.assertRaisesRegex(TypeError, expected):
unpickled_optional(a=1,b=2)
self.assertEqual(unpickled_defaults(), (1,2))
expected = r"global_pos_only_defaults\(\) got some positional-only arguments "\
r"passed as keyword arguments: 'a'"
with self.assertRaisesRegex(TypeError, expected):
unpickled_defaults(a=1,b=2)
def test_async(self):
async def f(a=1, /, b=2):
return a, b
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'a'"):
f(a=1, b=2)
def _check_call(*args, **kwargs):
try:
coro = f(*args, **kwargs)
coro.send(None)
except StopIteration as e:
result = e.value
self.assertEqual(result, (1, 2))
_check_call(1, 2)
_check_call(1, b=2)
_check_call(1)
_check_call()
def test_generator(self):
def f(a=1, /, b=2):
yield a, b
with self.assertRaisesRegex(TypeError, r"f\(\) got some positional-only arguments passed as keyword arguments: 'a'"):
f(a=1, b=2)
gen = f(1, 2)
self.assertEqual(next(gen), (1, 2))
gen = f(1, b=2)
self.assertEqual(next(gen), (1, 2))
gen = f(1)
self.assertEqual(next(gen), (1, 2))
gen = f()
self.assertEqual(next(gen), (1, 2))
def test_super(self):
sentinel = object()
class A:
def method(self):
return sentinel
class C(A):
def method(self, /):
return super().method()
self.assertEqual(C().method(), sentinel)
def test_annotations_constant_fold(self):
def g():
def f(x: not (int is int), /): ...
# without constant folding we end up with
# COMPARE_OP(is), IS_OP (0)
# with constant folding we should expect a IS_OP (1)
codes = [(i.opname, i.argval) for i in dis.get_instructions(g)]
self.assertNotIn(('UNARY_NOT', None), codes)
self.assertIn(('IS_OP', 1), codes)
if __name__ == "__main__":
unittest.main()