298 lines
7.5 KiB
Python
298 lines
7.5 KiB
Python
# SPDX-License-Identifier: MIT
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"""
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Tests for `attr.converters`.
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"""
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import pickle
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import pytest
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import attr
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from attr import Converter, Factory, attrib
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from attr._compat import _AnnotationExtractor
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from attr.converters import default_if_none, optional, pipe, to_bool
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class TestConverter:
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@pytest.mark.parametrize("takes_self", [True, False])
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@pytest.mark.parametrize("takes_field", [True, False])
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def test_pickle(self, takes_self, takes_field):
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"""
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Wrapped converters can be pickled.
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"""
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c = Converter(int, takes_self=takes_self, takes_field=takes_field)
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new_c = pickle.loads(pickle.dumps(c))
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assert c == new_c
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assert takes_self == new_c.takes_self
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assert takes_field == new_c.takes_field
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assert c.__call__.__name__ == new_c.__call__.__name__
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@pytest.mark.parametrize(
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"scenario",
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[
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((False, False), "__attr_converter_le_name(le_value)"),
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(
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(True, True),
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"__attr_converter_le_name(le_value, self, attr_dict['le_name'])",
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),
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(
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(True, False),
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"__attr_converter_le_name(le_value, self)",
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),
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(
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(False, True),
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"__attr_converter_le_name(le_value, attr_dict['le_name'])",
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),
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],
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)
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def test_fmt_converter_call(self, scenario):
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"""
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_fmt_converter_call determines the arguments to the wrapped converter
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according to `takes_self` and `takes_field`.
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"""
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(takes_self, takes_field), expect = scenario
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c = Converter(None, takes_self=takes_self, takes_field=takes_field)
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assert expect == c._fmt_converter_call("le_name", "le_value")
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def test_works_as_adapter(self):
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"""
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Converter instances work as adapters and pass the correct arguments to
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the wrapped converter callable.
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"""
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taken = None
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instance = object()
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field = object()
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def save_args(*args):
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nonlocal taken
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taken = args
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return args[0]
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Converter(save_args)(42, instance, field)
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assert (42,) == taken
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Converter(save_args, takes_self=True)(42, instance, field)
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assert (42, instance) == taken
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Converter(save_args, takes_field=True)(42, instance, field)
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assert (42, field) == taken
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Converter(save_args, takes_self=True, takes_field=True)(
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42, instance, field
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)
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assert (42, instance, field) == taken
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def test_annotations_if_last_in_pipe(self):
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"""
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If the wrapped converter has annotations, they are copied to the
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Converter __call__.
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"""
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def wrapped(_, __, ___) -> float:
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pass
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c = Converter(wrapped)
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assert float is c.__call__.__annotations__["return"]
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# Doesn't overwrite globally.
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c2 = Converter(int)
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assert float is c.__call__.__annotations__["return"]
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assert None is c2.__call__.__annotations__.get("return")
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class TestOptional:
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"""
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Tests for `optional`.
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"""
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def test_success_with_type(self):
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"""
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Wrapped converter is used as usual if value is not None.
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"""
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c = optional(int)
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assert c("42") == 42
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def test_success_with_none(self):
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"""
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Nothing happens if None.
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"""
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c = optional(int)
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assert c(None) is None
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def test_fail(self):
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"""
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Propagates the underlying conversion error when conversion fails.
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"""
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c = optional(int)
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with pytest.raises(ValueError):
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c("not_an_int")
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class TestDefaultIfNone:
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def test_missing_default(self):
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"""
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Raises TypeError if neither default nor factory have been passed.
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"""
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with pytest.raises(TypeError, match="Must pass either"):
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default_if_none()
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def test_too_many_defaults(self):
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"""
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Raises TypeError if both default and factory are passed.
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"""
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with pytest.raises(TypeError, match="but not both"):
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default_if_none(True, lambda: 42)
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def test_factory_takes_self(self):
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"""
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Raises ValueError if passed Factory has takes_self=True.
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"""
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with pytest.raises(ValueError, match="takes_self"):
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default_if_none(Factory(list, takes_self=True))
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@pytest.mark.parametrize("val", [1, 0, True, False, "foo", "", object()])
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def test_not_none(self, val):
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"""
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If a non-None value is passed, it's handed down.
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"""
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c = default_if_none("nope")
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assert val == c(val)
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c = default_if_none(factory=list)
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assert val == c(val)
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def test_none_value(self):
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"""
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Default values are returned when a None is passed.
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"""
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c = default_if_none(42)
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assert 42 == c(None)
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def test_none_factory(self):
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"""
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Factories are used if None is passed.
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"""
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c = default_if_none(factory=list)
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assert [] == c(None)
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c = default_if_none(default=Factory(list))
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assert [] == c(None)
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class TestPipe:
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def test_success(self):
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"""
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Succeeds if all wrapped converters succeed.
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"""
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c = pipe(str, Converter(to_bool), bool)
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assert (
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True
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is c.converter("True", None, None)
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is c.converter(True, None, None)
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)
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def test_fail(self):
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"""
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Fails if any wrapped converter fails.
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"""
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c = pipe(str, to_bool)
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# First wrapped converter fails:
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with pytest.raises(ValueError):
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c.converter(33, None, None)
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# Last wrapped converter fails:
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with pytest.raises(ValueError):
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c.converter("33", None, None)
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def test_sugar(self):
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"""
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`pipe(c1, c2, c3)` and `[c1, c2, c3]` are equivalent.
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"""
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@attr.s
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class C:
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a1 = attrib(default="True", converter=pipe(str, to_bool, bool))
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a2 = attrib(default=True, converter=[str, to_bool, bool])
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c = C()
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assert True is c.a1 is c.a2
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def test_empty(self):
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"""
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Empty pipe returns same value.
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"""
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o = object()
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assert o is pipe().converter(o, None, None)
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def test_wrapped_annotation(self):
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"""
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The return type of the wrapped converter is copied into its __call__
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and ultimately into pipe's wrapped converter.
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"""
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def last(value) -> bool:
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return bool(value)
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@attr.s
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class C:
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x = attr.ib(converter=[Converter(int), Converter(last)])
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i = C(5)
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assert True is i.x
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assert (
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bool
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is _AnnotationExtractor(
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attr.fields(C).x.converter.__call__
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).get_return_type()
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)
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class TestToBool:
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def test_unhashable(self):
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"""
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Fails if value is unhashable.
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"""
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with pytest.raises(ValueError, match="Cannot convert value to bool"):
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to_bool([])
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def test_truthy(self):
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"""
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Fails if truthy values are incorrectly converted.
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"""
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assert to_bool("t")
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assert to_bool("yes")
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assert to_bool("on")
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def test_falsy(self):
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"""
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Fails if falsy values are incorrectly converted.
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"""
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assert not to_bool("f")
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assert not to_bool("no")
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assert not to_bool("off")
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