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`blocking-open-call-in-async-function` (`ASYNC230`)

crates/ruff_linter/resources/mdtest/flake8-async/blocking-open-call-in-async-function.md

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blocking-open-call-in-async-function (ASYNC230)

toml
lint.select = ["ASYNC230"]

Builtin imports

Opening a file blocks an async function whether open is referenced directly, through builtins, or through an imported alias. io.open is also a blocking call.

py
import builtins
import io
from builtins import open as builtin_open

async def read_file():
    open("data.txt")  # error: [blocking-open-call-in-async-function]
    builtins.open("data.txt")  # error: [blocking-open-call-in-async-function]
    builtin_open("data.txt")  # error: [blocking-open-call-in-async-function]
    io.open("data.txt")  # error: [blocking-open-call-in-async-function]

Synchronous functions

The rule only checks calls in async contexts.

py
import builtins

def read_file():
    builtins.open("data.txt")

Shadowed names

A parameter named open does not refer to the builtin.

py
async def custom_open(open):
    open("data.txt")