425 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
		
			Executable File
		
	
			
		
		
	
	
			425 lines
		
	
	
		
			14 KiB
		
	
	
	
		
			Python
		
	
	
		
			Executable File
		
	
| #! /usr/bin/env python
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| # Copyright 2022 The Matrix.org Foundation C.I.C.
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| #
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| # Licensed under the Apache License, Version 2.0 (the "License");
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| # you may not use this file except in compliance with the License.
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| # You may obtain a copy of the License at
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| #
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| #     http://www.apache.org/licenses/LICENSE-2.0
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| #
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| # Unless required by applicable law or agreed to in writing, software
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| # distributed under the License is distributed on an "AS IS" BASIS,
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| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| # See the License for the specific language governing permissions and
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| # limitations under the License.
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| """
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| A script which enforces that Synapse always uses strict types when defining a Pydantic
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| model.
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| 
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| Pydantic does not yet offer a strict mode, but it is planned for pydantic v2. See
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| 
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|     https://github.com/pydantic/pydantic/issues/1098
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|     https://pydantic-docs.helpmanual.io/blog/pydantic-v2/#strict-mode
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| 
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| until then, this script is a best effort to stop us from introducing type coersion bugs
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| (like the infamous stringy power levels fixed in room version 10).
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| """
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| import argparse
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| import contextlib
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| import functools
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| import importlib
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| import logging
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| import os
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| import pkgutil
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| import sys
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| import textwrap
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| import traceback
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| import unittest.mock
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| from contextlib import contextmanager
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| from typing import Any, Callable, Dict, Generator, List, Set, Type, TypeVar
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| 
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| from parameterized import parameterized
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| from pydantic import BaseModel as PydanticBaseModel, conbytes, confloat, conint, constr
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| from pydantic.typing import get_args
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| from typing_extensions import ParamSpec
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| 
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| logger = logging.getLogger(__name__)
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| 
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| CONSTRAINED_TYPE_FACTORIES_WITH_STRICT_FLAG: List[Callable] = [
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|     constr,
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|     conbytes,
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|     conint,
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|     confloat,
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| ]
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| 
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| TYPES_THAT_PYDANTIC_WILL_COERCE_TO = [
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|     str,
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|     bytes,
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|     int,
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|     float,
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|     bool,
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| ]
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| 
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| 
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| P = ParamSpec("P")
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| R = TypeVar("R")
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| 
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| 
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| class ModelCheckerException(Exception):
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|     """Dummy exception. Allows us to detect unwanted types during a module import."""
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| 
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| 
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| class MissingStrictInConstrainedTypeException(ModelCheckerException):
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|     factory_name: str
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| 
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|     def __init__(self, factory_name: str):
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|         self.factory_name = factory_name
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| 
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| 
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| class FieldHasUnwantedTypeException(ModelCheckerException):
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|     message: str
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| 
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|     def __init__(self, message: str):
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|         self.message = message
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| 
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| 
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| def make_wrapper(factory: Callable[P, R]) -> Callable[P, R]:
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|     """We patch `constr` and friends with wrappers that enforce strict=True."""
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| 
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|     @functools.wraps(factory)
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|     def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
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|         if "strict" not in kwargs:
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|             raise MissingStrictInConstrainedTypeException(factory.__name__)
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|         if not kwargs["strict"]:
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|             raise MissingStrictInConstrainedTypeException(factory.__name__)
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|         return factory(*args, **kwargs)
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| 
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|     return wrapper
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| 
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| 
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| def field_type_unwanted(type_: Any) -> bool:
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|     """Very rough attempt to detect if a type is unwanted as a Pydantic annotation.
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| 
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|     At present, we exclude types which will coerce, or any generic type involving types
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|     which will coerce."""
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|     logger.debug("Is %s unwanted?")
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|     if type_ in TYPES_THAT_PYDANTIC_WILL_COERCE_TO:
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|         logger.debug("yes")
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|         return True
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|     logger.debug("Maybe. Subargs are %s", get_args(type_))
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|     rv = any(field_type_unwanted(t) for t in get_args(type_))
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|     logger.debug("Conclusion: %s %s unwanted", type_, "is" if rv else "is not")
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|     return rv
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| 
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| 
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| class PatchedBaseModel(PydanticBaseModel):
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|     """A patched version of BaseModel that inspects fields after models are defined.
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| 
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|     We complain loudly if we see an unwanted type.
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| 
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|     Beware: ModelField.type_ is presumably private; this is likely to be very brittle.
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|     """
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| 
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|     @classmethod
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|     def __init_subclass__(cls: Type[PydanticBaseModel], **kwargs: object):
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|         for field in cls.__fields__.values():
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|             # Note that field.type_ and field.outer_type are computed based on the
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|             # annotation type, see pydantic.fields.ModelField._type_analysis
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|             if field_type_unwanted(field.outer_type_):
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|                 # TODO: this only reports the first bad field. Can we find all bad ones
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|                 #  and report them all?
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|                 raise FieldHasUnwantedTypeException(
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|                     f"{cls.__module__}.{cls.__qualname__} has field '{field.name}' "
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|                     f"with unwanted type `{field.outer_type_}`"
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|                 )
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| 
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| 
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| @contextmanager
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| def monkeypatch_pydantic() -> Generator[None, None, None]:
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|     """Patch pydantic with our snooping versions of BaseModel and the con* functions.
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| 
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|     If the snooping functions see something they don't like, they'll raise a
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|     ModelCheckingException instance.
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|     """
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|     with contextlib.ExitStack() as patches:
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|         # Most Synapse code ought to import the patched objects directly from
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|         # `pydantic`. But we also patch their containing modules `pydantic.main` and
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|         # `pydantic.types` for completeness.
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|         patch_basemodel1 = unittest.mock.patch(
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|             "pydantic.BaseModel", new=PatchedBaseModel
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|         )
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|         patch_basemodel2 = unittest.mock.patch(
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|             "pydantic.main.BaseModel", new=PatchedBaseModel
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|         )
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|         patches.enter_context(patch_basemodel1)
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|         patches.enter_context(patch_basemodel2)
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|         for factory in CONSTRAINED_TYPE_FACTORIES_WITH_STRICT_FLAG:
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|             wrapper: Callable = make_wrapper(factory)
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|             patch1 = unittest.mock.patch(f"pydantic.{factory.__name__}", new=wrapper)
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|             patch2 = unittest.mock.patch(
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|                 f"pydantic.types.{factory.__name__}", new=wrapper
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|             )
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|             patches.enter_context(patch1)
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|             patches.enter_context(patch2)
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|         yield
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| 
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| 
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| def format_model_checker_exception(e: ModelCheckerException) -> str:
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|     """Work out which line of code caused e. Format the line in a human-friendly way."""
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|     # TODO. FieldHasUnwantedTypeException gives better error messages. Can we ditch the
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|     #   patches of constr() etc, and instead inspect fields to look for ConstrainedStr
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|     #   with strict=False? There is some difficulty with the inheritance hierarchy
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|     #   because StrictStr < ConstrainedStr < str.
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|     if isinstance(e, FieldHasUnwantedTypeException):
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|         return e.message
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|     elif isinstance(e, MissingStrictInConstrainedTypeException):
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|         frame_summary = traceback.extract_tb(e.__traceback__)[-2]
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|         return (
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|             f"Missing `strict=True` from {e.factory_name}() call \n"
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|             + traceback.format_list([frame_summary])[0].lstrip()
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|         )
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|     else:
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|         raise ValueError(f"Unknown exception {e}") from e
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| 
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| 
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| def lint() -> int:
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|     """Try to import all of Synapse and see if we spot any Pydantic type coercions.
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| 
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|     Print any problems, then return a status code suitable for sys.exit."""
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|     failures = do_lint()
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|     if failures:
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|         print(f"Found {len(failures)} problem(s)")
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|     for failure in sorted(failures):
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|         print(failure)
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|     return os.EX_DATAERR if failures else os.EX_OK
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| 
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| 
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| def do_lint() -> Set[str]:
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|     """Try to import all of Synapse and see if we spot any Pydantic type coercions."""
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|     failures = set()
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| 
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|     with monkeypatch_pydantic():
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|         logger.debug("Importing synapse")
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|         try:
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|             # TODO: make "synapse" an argument so we can target this script at
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|             # a subpackage
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|             module = importlib.import_module("synapse")
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|         except ModelCheckerException as e:
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|             logger.warning("Bad annotation found when importing synapse")
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|             failures.add(format_model_checker_exception(e))
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|             return failures
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| 
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|         try:
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|             logger.debug("Fetching subpackages")
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|             module_infos = list(
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|                 pkgutil.walk_packages(module.__path__, f"{module.__name__}.")
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|             )
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|         except ModelCheckerException as e:
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|             logger.warning("Bad annotation found when looking for modules to import")
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|             failures.add(format_model_checker_exception(e))
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|             return failures
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| 
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|         for module_info in module_infos:
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|             logger.debug("Importing %s", module_info.name)
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|             try:
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|                 importlib.import_module(module_info.name)
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|             except ModelCheckerException as e:
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|                 logger.warning(
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|                     f"Bad annotation found when importing {module_info.name}"
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|                 )
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|                 failures.add(format_model_checker_exception(e))
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| 
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|     return failures
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| 
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| 
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| def run_test_snippet(source: str) -> None:
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|     """Exec a snippet of source code in an isolated environment."""
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|     # To emulate `source` being called at the top level of the module,
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|     # the globals and locals we provide apparently have to be the same mapping.
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|     #
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|     # > Remember that at the module level, globals and locals are the same dictionary.
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|     # > If exec gets two separate objects as globals and locals, the code will be
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|     # > executed as if it were embedded in a class definition.
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|     globals_: Dict[str, object]
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|     locals_: Dict[str, object]
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|     globals_ = locals_ = {}
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|     exec(textwrap.dedent(source), globals_, locals_)
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| 
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| 
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| class TestConstrainedTypesPatch(unittest.TestCase):
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|     def test_expression_without_strict_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import constr
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|                 constr()
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|                 """
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|             )
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| 
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|     def test_called_as_module_attribute_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 import pydantic
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|                 pydantic.constr()
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|                 """
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|             )
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| 
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|     def test_wildcard_import_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import *
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|                 constr()
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|                 """
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|             )
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| 
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|     def test_alternative_import_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic.types import constr
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|                 constr()
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|                 """
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|             )
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| 
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|     def test_alternative_import_attribute_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 import pydantic.types
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|                 pydantic.types.constr()
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|                 """
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|             )
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| 
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|     def test_kwarg_but_no_strict_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import constr
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|                 constr(min_length=10)
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|                 """
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|             )
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| 
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|     def test_kwarg_strict_False_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import constr
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|                 constr(strict=False)
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|                 """
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|             )
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| 
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|     def test_kwarg_strict_True_doesnt_raise(self) -> None:
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|         with monkeypatch_pydantic():
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|             run_test_snippet(
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|                 """
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|                 from pydantic import constr
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|                 constr(strict=True)
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|                 """
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|             )
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| 
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|     def test_annotation_without_strict_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import constr
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|                 x: constr()
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|                 """
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|             )
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| 
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|     def test_field_annotation_without_strict_raises(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic import BaseModel, conint
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|                 class C:
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|                     x: conint()
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|                 """
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|             )
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| 
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| 
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| class TestFieldTypeInspection(unittest.TestCase):
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|     @parameterized.expand(
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|         [
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|             ("str",),
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|             ("bytes"),
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|             ("int",),
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|             ("float",),
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|             ("bool"),
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|             ("Optional[str]",),
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|             ("Union[None, str]",),
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|             ("List[str]",),
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|             ("List[List[str]]",),
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|             ("Dict[StrictStr, str]",),
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|             ("Dict[str, StrictStr]",),
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|             ("TypedDict('D', x=int)",),
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|         ]
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|     )
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|     def test_field_holding_unwanted_type_raises(self, annotation: str) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 f"""
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|                 from typing import *
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|                 from pydantic import *
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|                 class C(BaseModel):
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|                     f: {annotation}
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|                 """
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|             )
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| 
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|     @parameterized.expand(
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|         [
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|             ("StrictStr",),
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|             ("StrictBytes"),
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|             ("StrictInt",),
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|             ("StrictFloat",),
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|             ("StrictBool"),
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|             ("constr(strict=True, min_length=10)",),
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|             ("Optional[StrictStr]",),
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|             ("Union[None, StrictStr]",),
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|             ("List[StrictStr]",),
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|             ("List[List[StrictStr]]",),
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|             ("Dict[StrictStr, StrictStr]",),
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|             ("TypedDict('D', x=StrictInt)",),
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|         ]
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|     )
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|     def test_field_holding_accepted_type_doesnt_raise(self, annotation: str) -> None:
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|         with monkeypatch_pydantic():
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|             run_test_snippet(
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|                 f"""
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|                 from typing import *
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|                 from pydantic import *
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|                 class C(BaseModel):
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|                     f: {annotation}
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|                 """
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|             )
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| 
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|     def test_field_holding_str_raises_with_alternative_import(self) -> None:
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|         with monkeypatch_pydantic(), self.assertRaises(ModelCheckerException):
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|             run_test_snippet(
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|                 """
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|                 from pydantic.main import BaseModel
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|                 class C(BaseModel):
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|                     f: str
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|                 """
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|             )
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| 
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| 
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| parser = argparse.ArgumentParser()
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| parser.add_argument("mode", choices=["lint", "test"], default="lint", nargs="?")
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| parser.add_argument("-v", "--verbose", action="store_true")
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| 
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| 
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| if __name__ == "__main__":
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|     args = parser.parse_args(sys.argv[1:])
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|     logging.basicConfig(
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|         format="%(asctime)s %(name)s:%(lineno)d %(levelname)s %(message)s",
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|         level=logging.DEBUG if args.verbose else logging.INFO,
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|     )
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|     # suppress logs we don't care about
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|     logging.getLogger("xmlschema").setLevel(logging.WARNING)
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|     if args.mode == "lint":
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|         sys.exit(lint())
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|     elif args.mode == "test":
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|         unittest.main(argv=sys.argv[:1])
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