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# SPDX-License-Identifier: MIT
# Keep this file SHORT, until Black can handle it.
import pytest
import attr
class TestPatternMatching:
"""
Pattern matching syntax test cases.
"""
@pytest.mark.parametrize("dec", [attr.s, attr.define, attr.frozen])
def test_simple_match_case(self, dec):
"""
Simple match case statement works as expected with all class
decorators.
"""
@dec
class C(object):
a = attr.ib()
assert ("a",) == C.__match_args__
matched = False
c = C(a=1)
match c:
case C(a):
matched = True
assert matched
assert 1 == a
def test_explicit_match_args(self):
"""
Does not overwrite a manually set empty __match_args__.
"""
ma = ()
@attr.define
class C:
a = attr.field()
__match_args__ = ma
c = C(a=1)
msg = r"C\(\) accepts 0 positional sub-patterns \(1 given\)"
with pytest.raises(TypeError, match=msg):
match c:
case C(_):
pass
def test_match_args_kw_only(self):
"""
kw_only classes don't generate __match_args__.
kw_only fields are not included in __match_args__.
"""
@attr.define
class C:
a = attr.field(kw_only=True)
b = attr.field()
assert ("b",) == C.__match_args__
c = C(a=1, b=1)
msg = r"C\(\) accepts 1 positional sub-pattern \(2 given\)"
with pytest.raises(TypeError, match=msg):
match c:
case C(a, b):
pass
found = False
match c:
case C(b, a=a):
found = True
assert found
@attr.define(kw_only=True)
class C:
a = attr.field()
b = attr.field()
c = C(a=1, b=1)
msg = r"C\(\) accepts 0 positional sub-patterns \(2 given\)"
with pytest.raises(TypeError, match=msg):
match c:
case C(a, b):
pass
found = False
match c:
case C(a=a, b=b):
found = True
assert found
assert (1, 1) == (a, b)