# Ignore Early-Canceled Tests Example
URL: /examples/ignore-early-canceled-tests

The upstream ignore_early_canceled_tests.py example — subclass OutputToJSON to skip writing records for tests aborted (Ctrl-C) before an operator entered a DUT ID, using default_dut_id.

A station that waits for a barcode scan produces a useless record every time someone presses Ctrl-C at the prompt. This example filters those out in the output callback. Based on `examples/ignore_early_canceled_tests.py`.

Press Ctrl-C *after* entering a DUT ID and the record is written, because the abort then carries information about a real unit.

An output callback is any callable taking a `TestRecord`. Subclassing the built-in keeps its file-pattern handling and lets you add a condition in `__call__`. Custom output →

Set when the run ends on `KeyboardInterrupt` (SIGINT). Other exceptions give `ERROR` and are kept — they may be worth debugging. Test outcomes →

A recognisable sentinel instead of the default `UNKNOWN_DUT`, so the callback can tell "never scanned" from "scanned, then aborted". Test Options →

OpenHTF's console helper; respects the CLI colour settings and does not interleave badly with the logger.

The same shape filters records for any reason — skip uploads for `station_id == 'dev-bench'`, write `FAIL` records to a second directory, or add a retry around a network upload. TofuPilot's `upload()` callback can be wrapped the same way. Output Callbacks →

<Card title="Output Callbacks" href="/output-callbacks" description="JSON, console, database." />

<Card title="Device Under Test" href="/dut" description="Prompting, validating and defaulting the DUT ID." />