"""Wrapper for inline_snapshot that uses lightweight stubs by default.
inline_snapshot is expensive to import and has heavy startup overhead (AST rewriting, etc.)
that significantly slows pytest-xdist worker initialization, especially on Python 3.10.
When no --inline-snapshot flag is passed to pytest, we use lightweight stubs:
- snapshot(value) returns a proxy that compares using the value, warning on mismatch
- snapshot() with no args raises an error directing you to use --inline-snapshot=create
- Is(value) compares using the underlying value
- customize_repr is a no-op decorator
Pass --inline-snapshot=<mode> or --snap/--snap-fix to use the real library.
"""
from __future__ import annotations
import sys
import warnings
from collections.abc import Iterator
from contextlib import contextmanager
from typing import TYPE_CHECKING, Any
from warnings import catch_warnings, simplefilter
if TYPE_CHECKING:
from inline_snapshot import (
Is as Is,
customize_repr as customize_repr, # pyright: ignore[reportUnknownVariableType]
snapshot as snapshot,
)
from inline_snapshot.extra import raises as raises, warns as warns
elif any(arg.startswith('--inline-snapshot') or arg.startswith('--snap') for arg in sys.argv):
from inline_snapshot import (
Is as Is,
customize_repr as customize_repr, # pyright: ignore[reportUnknownVariableType]
snapshot as snapshot,
)
from inline_snapshot.extra import raises as raises, warns as warns
else:
class _SnapshotProxy:
"""Proxy that compares using the snapshot value, warning on mismatch."""
def __init__(self, value: Any) -> None:
self._value = value
def __repr__(self) -> str:
return repr(self._value)
def __eq__(self, other: object) -> bool:
result = other == self._value
if not result:
warnings.warn(
f'Snapshot mismatch: {other!r} != {self._value!r}\n'
'Re-run with --inline-snapshot=fix to update snapshots.',
stacklevel=2,
)
return result # type: ignore[return-value]
_MISSING = object()
def snapshot(value: Any = _MISSING) -> Any:
if value is _MISSING:
raise RuntimeError(
'snapshot() called without a value. Run with --inline-snapshot=create to generate initial snapshots.'
)
return _SnapshotProxy(value)
class Is:
def __init__(self, value: Any) -> None:
self.value = value
def __repr__(self) -> str:
return f'Is({self.value!r})'
def __eq__(self, other: object) -> bool:
return other == self.value
def customize_repr(func: Any) -> Any:
return func
@contextmanager
def warns(expected_warnings: Any, /, include_line: bool = False, include_file: bool = False) -> Iterator[None]:
with catch_warnings(record=True) as caught:
simplefilter('always')
yield
formatted: list[str] = []
for w in caught:
parts: list[str] = []
if include_file:
parts.append(w.filename)
if include_line:
parts.append(str(w.lineno))
parts.append(f'{w.category.__name__}: {w.message}')
formatted.append(', '.join(parts) if len(parts) > 1 else parts[0])
assert formatted == expected_warnings
@contextmanager
def raises(exception: Any) -> Iterator[None]:
try:
yield
except Exception as e:
actual = f'{type(e).__name__}: {e}'
else:
actual = '<no exception>'
assert actual == exception
