239 lines
8.4 KiB
Python
239 lines
8.4 KiB
Python
""" recording warnings during test function execution. """
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from __future__ import absolute_import, division, print_function
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import inspect
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import _pytest._code
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import py
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import sys
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import warnings
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import re
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from _pytest.fixtures import yield_fixture
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from _pytest.outcomes import fail
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@yield_fixture
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def recwarn():
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"""Return a WarningsRecorder instance that provides these methods:
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* ``pop(category=None)``: return last warning matching the category.
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* ``clear()``: clear list of warnings
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See http://docs.python.org/library/warnings.html for information
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on warning categories.
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"""
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wrec = WarningsRecorder()
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with wrec:
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warnings.simplefilter('default')
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yield wrec
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def deprecated_call(func=None, *args, **kwargs):
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"""context manager that can be used to ensure a block of code triggers a
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``DeprecationWarning`` or ``PendingDeprecationWarning``::
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>>> import warnings
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>>> def api_call_v2():
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... warnings.warn('use v3 of this api', DeprecationWarning)
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... return 200
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>>> with deprecated_call():
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... assert api_call_v2() == 200
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``deprecated_call`` can also be used by passing a function and ``*args`` and ``*kwargs``,
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in which case it will ensure calling ``func(*args, **kwargs)`` produces one of the warnings
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types above.
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"""
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if not func:
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return _DeprecatedCallContext()
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else:
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__tracebackhide__ = True
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with _DeprecatedCallContext():
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return func(*args, **kwargs)
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class _DeprecatedCallContext(object):
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"""Implements the logic to capture deprecation warnings as a context manager."""
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def __enter__(self):
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self._captured_categories = []
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self._old_warn = warnings.warn
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self._old_warn_explicit = warnings.warn_explicit
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warnings.warn_explicit = self._warn_explicit
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warnings.warn = self._warn
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def _warn_explicit(self, message, category, *args, **kwargs):
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self._captured_categories.append(category)
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def _warn(self, message, category=None, *args, **kwargs):
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if isinstance(message, Warning):
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self._captured_categories.append(message.__class__)
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else:
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self._captured_categories.append(category)
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def __exit__(self, exc_type, exc_val, exc_tb):
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warnings.warn_explicit = self._old_warn_explicit
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warnings.warn = self._old_warn
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if exc_type is None:
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deprecation_categories = (DeprecationWarning, PendingDeprecationWarning)
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if not any(issubclass(c, deprecation_categories) for c in self._captured_categories):
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__tracebackhide__ = True
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msg = "Did not produce DeprecationWarning or PendingDeprecationWarning"
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raise AssertionError(msg)
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def warns(expected_warning, *args, **kwargs):
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"""Assert that code raises a particular class of warning.
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Specifically, the input @expected_warning can be a warning class or
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tuple of warning classes, and the code must return that warning
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(if a single class) or one of those warnings (if a tuple).
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This helper produces a list of ``warnings.WarningMessage`` objects,
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one for each warning raised.
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This function can be used as a context manager, or any of the other ways
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``pytest.raises`` can be used::
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>>> with warns(RuntimeWarning):
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... warnings.warn("my warning", RuntimeWarning)
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In the context manager form you may use the keyword argument ``match`` to assert
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that the exception matches a text or regex::
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>>> with warns(UserWarning, match='must be 0 or None'):
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... warnings.warn("value must be 0 or None", UserWarning)
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>>> with warns(UserWarning, match=r'must be \d+$'):
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... warnings.warn("value must be 42", UserWarning)
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>>> with warns(UserWarning, match=r'must be \d+$'):
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... warnings.warn("this is not here", UserWarning)
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Traceback (most recent call last):
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...
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Failed: DID NOT WARN. No warnings of type ...UserWarning... was emitted...
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"""
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match_expr = None
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if not args:
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if "match" in kwargs:
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match_expr = kwargs.pop("match")
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return WarningsChecker(expected_warning, match_expr=match_expr)
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elif isinstance(args[0], str):
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code, = args
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assert isinstance(code, str)
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frame = sys._getframe(1)
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loc = frame.f_locals.copy()
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loc.update(kwargs)
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with WarningsChecker(expected_warning, match_expr=match_expr):
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code = _pytest._code.Source(code).compile()
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py.builtin.exec_(code, frame.f_globals, loc)
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else:
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func = args[0]
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with WarningsChecker(expected_warning, match_expr=match_expr):
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return func(*args[1:], **kwargs)
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class WarningsRecorder(warnings.catch_warnings):
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"""A context manager to record raised warnings.
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Adapted from `warnings.catch_warnings`.
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"""
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def __init__(self):
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super(WarningsRecorder, self).__init__(record=True)
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self._entered = False
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self._list = []
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@property
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def list(self):
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"""The list of recorded warnings."""
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return self._list
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def __getitem__(self, i):
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"""Get a recorded warning by index."""
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return self._list[i]
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def __iter__(self):
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"""Iterate through the recorded warnings."""
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return iter(self._list)
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def __len__(self):
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"""The number of recorded warnings."""
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return len(self._list)
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def pop(self, cls=Warning):
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"""Pop the first recorded warning, raise exception if not exists."""
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for i, w in enumerate(self._list):
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if issubclass(w.category, cls):
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return self._list.pop(i)
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__tracebackhide__ = True
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raise AssertionError("%r not found in warning list" % cls)
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def clear(self):
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"""Clear the list of recorded warnings."""
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self._list[:] = []
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def __enter__(self):
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if self._entered:
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__tracebackhide__ = True
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raise RuntimeError("Cannot enter %r twice" % self)
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self._list = super(WarningsRecorder, self).__enter__()
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warnings.simplefilter('always')
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return self
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def __exit__(self, *exc_info):
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if not self._entered:
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__tracebackhide__ = True
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raise RuntimeError("Cannot exit %r without entering first" % self)
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super(WarningsRecorder, self).__exit__(*exc_info)
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class WarningsChecker(WarningsRecorder):
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def __init__(self, expected_warning=None, match_expr=None):
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super(WarningsChecker, self).__init__()
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msg = ("exceptions must be old-style classes or "
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"derived from Warning, not %s")
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if isinstance(expected_warning, tuple):
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for exc in expected_warning:
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if not inspect.isclass(exc):
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raise TypeError(msg % type(exc))
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elif inspect.isclass(expected_warning):
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expected_warning = (expected_warning,)
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elif expected_warning is not None:
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raise TypeError(msg % type(expected_warning))
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self.expected_warning = expected_warning
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self.match_expr = match_expr
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def __exit__(self, *exc_info):
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super(WarningsChecker, self).__exit__(*exc_info)
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# only check if we're not currently handling an exception
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if all(a is None for a in exc_info):
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if self.expected_warning is not None:
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if not any(issubclass(r.category, self.expected_warning)
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for r in self):
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__tracebackhide__ = True
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fail("DID NOT WARN. No warnings of type {0} was emitted. "
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"The list of emitted warnings is: {1}.".format(
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self.expected_warning,
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[each.message for each in self]))
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elif self.match_expr is not None:
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for r in self:
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if issubclass(r.category, self.expected_warning):
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if re.compile(self.match_expr).search(str(r.message)):
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break
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else:
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fail("DID NOT WARN. No warnings of type {0} matching"
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" ('{1}') was emitted. The list of emitted warnings"
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" is: {2}.".format(
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self.expected_warning,
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self.match_expr,
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[each.message for each in self]))
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