dns

Signature

faultcore.dns(*, delay: str | None = None, timeout: str | None = None, nxdomain: str | None = None)

Purpose

Injects resolver-side DNS behavior for tests that resolve hostnames.

Parameters

• delay: duration string.

• timeout: duration string.

• nxdomain: probability string with % or ppm.

Defaults and validation

• All fields are optional.

• Duration fields must use ms/s.

Example (hostname resolution test)

import faultcore


@faultcore.dns(delay="40ms", nxdomain="3%")
def resolve_service(host: str) -> str:
    return host


def test_dns_failure_fallback() -> None:
    primary = resolve_service("api.internal")
    assert primary == "api.internal"