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from __future__ import annotations
from dataclasses import dataclass, fields, InitVar # NOQA
from textwrap import dedent
from io import BytesIO
from typing import ClassVar, Union
class TestDataClasses:
def test_1(self) -> None:
from ruamel.yaml import YAML
yaml = YAML()
@yaml.register_class
@dataclass
class DC:
abc: int
klm: int
xyz: int = 0
def __post_init__(self) -> None:
self.xyz = self.abc + self.klm
dc = DC(abc=5, klm=42)
assert dc.xyz == 47
yaml_str = dedent("""\
!DC
abc: 13
klm: 37
""")
dc2 = yaml.load(yaml_str)
assert dc2.xyz == 50
def test_yamltag(self) -> None:
from ruamel.yaml import YAML
yaml = YAML()
@yaml.register_class
@dataclass
class DC:
yaml_tag: ClassVar = '!dc_example'
abc: int
klm: int
dc = DC(abc=5, klm=42)
buf = BytesIO()
yaml.dump(dc, buf)
assert buf.getvalue() == dedent("""\
!dc_example
abc: 5
klm: 42
""").encode('utf-8')
dc2 = yaml.load(buf.getvalue())
assert len(fields(dc2)) == 2 # class var is not a field
assert dc2.abc == dc.abc
assert dc2.klm == dc.klm
def test_initvar(self) -> None:
from ruamel.yaml import YAML
yaml = YAML()
@yaml.register_class
@dataclass
class DC:
abc: int
klm: int
xyz: InitVar[Union[str, None]] = None
def __post_init__(self, xyz: Union[str, None]) -> None:
# assert xyz == self.xyz # self.xyz is always None
if xyz is not None:
self.klm += len(xyz)
dc = DC(abc=5, klm=42, xyz='provided')
# this actually doesn't raise an attribute error, I would have expected it not to work
# at all, but it has the default value
assert dc.xyz is None # type: ignore
buf = BytesIO()
yaml.dump(dc, buf)
assert buf.getvalue() == dedent("""\
!DC
abc: 5
klm: 50
""").encode('utf-8')
yaml_str = dedent("""\
!DC
abc: 18
klm: 55
xyz: some string
""")
dc2 = yaml.load(yaml_str)
assert dc2.xyz is None
assert dc2.klm == 55 + len('some string')
def test_initvar_not_in_yaml(self) -> None:
from ruamel.yaml import YAML
yaml = YAML()
@yaml.register_class
@dataclass
class DC:
abc: int
klm: int
xyz: InitVar[Union[str, None]] = 'hello'
def __post_init__(self, xyz: Union[str, None]) -> None:
# assert xyz == self.xyz # self.xyz is always None
if xyz is not None:
self.klm += len(xyz)
dc = DC(abc=5, klm=42, xyz='provided')
assert dc.abc == 5
assert dc.xyz == 'hello' # type: ignore
buf = BytesIO()
yaml.dump(dc, buf)
assert buf.getvalue() == dedent("""\
!DC
abc: 5
klm: 50
""").encode('utf-8')
yaml_str = dedent("""\
!DC
abc: 18
klm: 55
""")
dc2 = yaml.load(yaml_str)
assert dc2.xyz == 'hello'
assert dc2.klm == 55 + len('hello')
def test_collection_field(self) -> None:
# https://stackoverflow.com/a/77485786/1307905
import ruamel.yaml
from dataclasses import dataclass
@dataclass
class Msg:
id: int
desc: str
fields: list[Field]
def __post_init__(self) -> None:
idx: int = 0
for field in self.fields: # why is this empty??
field.index = idx
idx += field.size
@dataclass
class Field:
id: int
name: str
units: str
size: int
index: int = -1
yaml = ruamel.yaml.YAML()
yaml.register_class(Msg)
yaml.register_class(Field)
msg: Msg = yaml.load("""\
!Msg
id: 1
desc: status
fields:
- !Field
id: 1
name: Temp
units: degC
size: 2
""")
assert msg.fields[0].index != -1
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