"""Assertions for runtime type checking of function arguments."""
from typing import Any
from eth_utils import is_address
from web3.providers.base import BaseProvider
def assert_is_string(value: Any, name: str) -> None:
"""If :param value: isn't of type str, raise a TypeError.
>>> try: assert_is_string(123, 'var')
... except TypeError as type_error: print(str(type_error))
...
expected variable 'var', with value 123, to have type 'str', not 'int'
"""
if not isinstance(value, str):
raise TypeError(
f"expected variable '{name}', with value {str(value)}, to have"
+ f" type 'str', not '{type(value).__name__}'"
)
def assert_is_list(value: Any, name: str) -> None:
"""If :param value: isn't of type list, raise a TypeError.
>>> try: assert_is_list(123, 'var')
... except TypeError as type_error: print(str(type_error))
...
expected variable 'var', with value 123, to have type 'list', not 'int'
"""
if not isinstance(value, list):
raise TypeError(
f"expected variable '{name}', with value {str(value)}, to have"
+ f" type 'list', not '{type(value).__name__}'"
)
def assert_is_int(value: Any, name: str) -> None:
"""If :param value: isn't of type int, raise a TypeError.
>>> try: assert_is_int('asdf', 'var')
... except TypeError as type_error: print(str(type_error))
...
expected variable 'var', with value asdf, to have type 'int', not 'str'
"""
if not isinstance(value, int):
raise TypeError(
f"expected variable '{name}', with value {str(value)}, to have"
+ f" type 'int', not '{type(value).__name__}'"
)
def assert_is_hex_string(value: Any, name: str) -> None:
"""Assert that :param value: is a string of hex chars.
If :param value: isn't a str, raise a TypeError. If it is a string but
contains non-hex characters ("0x" prefix permitted), raise a ValueError.
"""
assert_is_string(value, name)
int(value, 16) # raises a ValueError if value isn't a base-16 str
def assert_is_address(value: Any, name: str) -> None:
"""Assert that `value` is a valid Ethereum address.
If `value` isn't a hex string, raise a TypeError. If it isn't a valid
Ethereum address, raise a ValueError.
"""
assert_is_hex_string(value, name)
if not is_address(value):
raise ValueError(
f"Expected variable '{name}' to be a valid Ethereum"
+ " address, but it's not."
)
def assert_is_provider(value: Any, name: str) -> None:
"""Assert that `value` is a Web3 provider.
If `value` isn't a Web3 provider, raise a TypeError.
"""
if not isinstance(value, BaseProvider):
raise TypeError(
f"Expected variable '{name}' to be an instance of a Web3 provider,"
+ " but it's not."
)