def _assert_invariant(contract: Contract, instance: Any) -> None:
"""Assert that the contract holds as a class invariant given the instance of the class."""
if 'self' in contract.condition_arg_set:
check = contract.condition(self=instance)
else:
check = contract.condition()
if _not_check(check=check, contract=contract):
if contract.error is not None and (inspect.ismethod(contract.error) or
inspect.isfunction(contract.error)):
assert contract.error_arg_set is not None, "Expected error_arg_set non-None if contract.error a function."
assert contract.error_args is not None, "Expected error_args non-None if contract.error a function."
if 'self' in contract.error_arg_set:
raise contract.error(self=instance)
else:
raise contract.error()
else:
if 'self' in contract.condition_arg_set:
msg = icontract._represent.generate_message(
contract=contract, condition_kwargs={"self": instance})
else:
msg = icontract._represent.generate_message(
contract=contract, condition_kwargs=dict())
if contract.error is None:
raise ViolationError(msg)
elif isinstance(contract.error, type):
raise contract.error(msg)
else:
raise NotImplementedError(
"Unhandled contract.error: {}".format(contract.error))
def _assert_precondition(contract: Contract,
resolved_kwargs: Mapping[str, Any]) -> None:
"""
Assert that the contract holds as a precondition.
:param contract: contract to be verified
:param resolved_kwargs:
resolved keyword arguments of the call (including the default argument values of the decorated function)
:return:
"""
condition_kwargs = select_condition_kwargs(contract=contract,
resolved_kwargs=resolved_kwargs)
check = contract.condition(**condition_kwargs)
if not_check(check=check, contract=contract):
if contract.error is not None and (inspect.ismethod(contract.error) or
inspect.isfunction(contract.error)):
assert contract.error_arg_set is not None, "Expected error_arg_set non-None if contract.error a function."
assert contract.error_args is not None, "Expected error_args non-None if contract.error a function."
error_kwargs = {
arg_name: value
for arg_name, value in resolved_kwargs.items()
if arg_name in contract.error_arg_set
}
missing_args = [
arg_name for arg_name in contract.error_args
if arg_name not in resolved_kwargs
]
if missing_args:
msg_parts = []
if contract.location is not None:
msg_parts.append("{}:\n".format(contract.location))
msg_parts.append((
"The argument(s) of the precondition error have not been set: {}. "
"Does the original function define them? Did you supply them in the call?"
).format(missing_args))
raise TypeError(''.join(msg_parts))
raise contract.error(**error_kwargs)
else:
msg = icontract._represent.generate_message(
contract=contract, condition_kwargs=condition_kwargs)
if contract.error is None:
raise ViolationError(msg)
elif isinstance(contract.error, type):
raise contract.error(msg)
def _create_violation_error(contract: Contract, resolved_kwargs: Mapping[str, Any]) -> BaseException:
"""Create the violation error based on the violated contract."""
exception = None # type: Optional[BaseException]
if contract.error is None:
try:
msg = icontract._represent.generate_message(contract=contract, resolved_kwargs=resolved_kwargs)
except Exception as err:
parts = ["Failed to recompute the values of the contract condition:\n"]
if contract.location is not None:
parts.append("{}:\n".format(contract.location))
if contract.description is not None:
parts.append("{}: ".format(contract.description))
parts.append(icontract._represent.represent_condition(condition=contract.condition))
raise RuntimeError(''.join(parts)) from err
exception = ViolationError(msg)
elif inspect.ismethod(contract.error) or inspect.isfunction(contract.error):
assert contract.error_arg_set is not None, ("Expected error_arg_set non-None if contract.error a function.")
assert contract.error_args is not None, ("Expected error_args non-None if contract.error a function.")
error_kwargs = select_error_kwargs(contract=contract, resolved_kwargs=resolved_kwargs)
exception = cast(BaseException, contract.error(**error_kwargs)) # type: ignore
if not isinstance(exception, BaseException):
raise TypeError(
"The exception returned by the contract's error {} does not inherit from BaseException.".format(
contract.error))
elif isinstance(contract.error, type):
if not issubclass(contract.error, BaseException):
raise TypeError(
"The exception class supplied in the contract's error {} is not a subclass of BaseException.".format(
contract.error))
msg = icontract._represent.generate_message(contract=contract, resolved_kwargs=resolved_kwargs)
exception = contract.error(msg)
elif isinstance(contract.error, BaseException):
exception = contract.error
else:
raise NotImplementedError(
("icontract does not know how to handle the error of type {} "
"(expected a function, a subclass of BaseException or an instance of BaseException)").format(
type(contract.error)))
assert exception is not None
return exception
def _assert_postcondition(contract: Contract,
resolved_kwargs: Mapping[str, Any]) -> None:
"""
Assert that the contract holds as a postcondition.
The arguments to the postcondition are given as ``resolved_kwargs`` which includes
both argument values captured in snapshots and actual argument values and the result of a function.
:param contract: contract to be verified
:param resolved_kwargs: resolved keyword arguments (including the default values, ``result`` and ``OLD``)
:return:
"""
assert 'result' in resolved_kwargs, \
"Expected 'result' to be set in the resolved keyword arguments of a postcondition."
# Check that all arguments to the condition function have been set.
missing_args = [
arg_name for arg_name in contract.mandatory_args
if arg_name not in resolved_kwargs
]
if missing_args:
msg_parts = [] # type: List[str]
if contract.location is not None:
msg_parts.append("{}:\n".format(contract.location))
msg_parts.append((
"The argument(s) of the postcondition have not been set: {}. "
"Does the original function define them? Did you supply them in the call?"
).format(missing_args))
raise TypeError(''.join(msg_parts))
condition_kwargs = {
arg_name: value
for arg_name, value in resolved_kwargs.items()
if arg_name in contract.condition_arg_set
}
check = contract.condition(**condition_kwargs)
if _not_check(check=check, contract=contract):
if contract.error is not None and (inspect.ismethod(contract.error) or
inspect.isfunction(contract.error)):
assert contract.error_arg_set is not None, "Expected error_arg_set non-None if contract.error a function."
assert contract.error_args is not None, "Expected error_args non-None if contract.error a function."
error_kwargs = {
arg_name: value
for arg_name, value in resolved_kwargs.items()
if arg_name in contract.error_arg_set
}
missing_args = [
arg_name for arg_name in contract.error_args
if arg_name not in resolved_kwargs
]
if missing_args:
msg_parts = []
if contract.location is not None:
msg_parts.append("{}:\n".format(contract.location))
msg_parts.append((
"The argument(s) of the postcondition error have not been set: {}. "
"Does the original function define them? Did you supply them in the call?"
).format(missing_args))
raise TypeError(''.join(msg_parts))
raise contract.error(**error_kwargs)
else:
msg = icontract._represent.generate_message(
contract=contract, condition_kwargs=condition_kwargs)
if contract.error is None:
raise ViolationError(msg)
elif isinstance(contract.error, type):
raise contract.error(msg)
