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Fix serialization of Enum and Path #203

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982b725
Fix serialization of Enum and Path
radoering Aug 6, 2025
9685398
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Aug 6, 2025
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10 changes: 9 additions & 1 deletion src/pytest_subtests/plugin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@
from contextlib import contextmanager
from contextlib import ExitStack
from contextlib import nullcontext
from enum import Enum
from pathlib import Path
from typing import Any
from typing import Callable
from typing import ContextManager
Expand Down Expand Up @@ -77,8 +79,14 @@ def sub_test_description(self) -> str:
def _to_json(self) -> dict:
data = super()._to_json()
del data["context"]

def serialize(inst: type, field: attr.Attribute, value: Any) -> Any:
if isinstance(value, (Enum, Path)):
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I think we should not special-case Enum and Path, seems subTest parameters are reported as::

  • The msg parameter is always converted to string using str().
  • The dict contents are converted to string using repr().

The example below uses a custom class to demonstrate that.

import unittest
from enum import StrEnum, auto, Enum


class MyEnum(Enum):
    A = 1
    B = 2

class C:
    def __str__(self):
        return "C:str"
    def __repr__(self):
        return "C:repr"


class MyUnitTest(unittest.TestCase):

    def test_enum_values(self):
        for value in (C(), MyEnum.B):
            with self.subTest(value, p=value):
                assert False

if __name__ == '__main__':
    unittest.main()
test_enum_values (__main__.MyUnitTest.test_enum_values) ...
  test_enum_values (__main__.MyUnitTest.test_enum_values) [C:str] (p=C:repr) ... FAIL
  test_enum_values (__main__.MyUnitTest.test_enum_values) [MyEnum.B] (p=<MyEnum.B: 2>) ... FAIL

Ideally, we should find a way to perform the same conversions (str for msg and repr for the rest) during serialization.

return str(value)
return value

data["_report_type"] = "SubTestReport"
data["_subtest.context"] = attr.asdict(self.context)
data["_subtest.context"] = attr.asdict(self.context, value_serializer=serialize)
return data

@classmethod
Expand Down
70 changes: 70 additions & 0 deletions tests/test_subtests.py
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,76 @@ def test_simple_terminal_verbose(
]
)

@pytest.mark.parametrize("runner", ["unittest", "pytest-normal", "pytest-xdist"])
def test_serialization(
self,
pytester: pytest.Pytester,
runner: Literal["unittest", "pytest-normal", "pytest-xdist"],
) -> None:
p = pytester.makepyfile(
"""
import sys
from unittest import TestCase, main
from pathlib import Path

if sys.version_info[:2] < (3, 11):
from enum import Enum

class MyEnum(str, Enum):
CUSTOM = "custom"

def __str__(self) -> str:
return self.value
else:
from enum import StrEnum

class MyEnum(StrEnum):
CUSTOM = "custom"

class T(TestCase):

def test_foo(self):
for i in range(5):
with self.subTest(msg=MyEnum.CUSTOM, i=i, p=Path("test")):
Comment on lines +301 to +304
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Just for being pedantic what happens if msg is dict of name to enum

Although i wouldn't expect people to use that people are always in for horrible surprises

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It seems to work - probably because attr.asdict() handles dicts per default by converting their elements: https://github.com/python-attrs/attrs/blob/a296a129c60f5c736165086621f03c10a4d14065/src/attr/_funcs.py#L104-L126

self.assertEqual(i % 2, 0)

if __name__ == '__main__':
main()
"""
)
suffix = ".test_foo" if IS_PY311 else ""
if runner == "unittest":
result = pytester.run(sys.executable, p)
result.stderr.fnmatch_lines(
[
f"FAIL: test_foo (__main__.T{suffix}) [[]custom[]] (i=1, p=*)",
"AssertionError: 1 != 0",
f"FAIL: test_foo (__main__.T{suffix}) [[]custom[]] (i=3, p=*)",
"AssertionError: 1 != 0",
"Ran 1 test in *",
"FAILED (failures=2)",
]
)
else:
if runner == "pytest-normal":
result = pytester.runpytest(p)
expected_lines = ["collected 1 item"]
else:
assert runner == "pytest-xdist"
pytest.importorskip("xdist")
result = pytester.runpytest(p, "-n1")
expected_lines = ["1 worker [1 item]"]
result.stdout.fnmatch_lines(
expected_lines
+ [
"* T.test_foo [[]custom[]] (i=1, p=*) *",
"E * AssertionError: 1 != 0",
"* T.test_foo [[]custom[]] (i=3, p=*) *",
"E * AssertionError: 1 != 0",
"* 2 failed, 1 passed, 3 subtests passed in *",
]
)

@pytest.mark.parametrize("runner", ["unittest", "pytest-normal", "pytest-xdist"])
def test_skip(
self,
Expand Down
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