Make command-line flag parsing robust to lookalike flags and bad values - #159
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`extract_flag!` matched flags with `startswith` and unconditionally indexed
the second element of an unbounded `split` on `=`, so:
- `--verbose-foo` threw a BoundsError instead of the friendly "Unknown test
options" message;
- a custom flag extending a builtin's name (e.g. `--listing` vs `--list`)
was captured by the builtin, also throwing a BoundsError;
- `--jobs2=3` was silently accepted as `--jobs=3`;
- a bare `--jobs` crashed with a MethodError when `Some(nothing)` hit the
`Some{Int}` field of `ParsedArgs`, and `--jobs=abc` leaked a raw
ArgumentError from `parse`;
- values containing `=` (e.g. `--format=key=value`) were truncated.
Match only the exact flag or `--flag=value`, split with `limit=2`, and turn
missing or unparseable values into clean error messages. Also reject values
passed to the boolean flags `--verbose`/`--quickfail`/`--list`, which
previously crashed with a MethodError during ParsedArgs construction.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
giordano
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Aug 8, 2026
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| # boolean flags don't take values | ||
| for (flag, val) in (("--verbose", verbose), ("--quickfail", quickfail), ("--list", list)) | ||
| if val isa Some && something(val) !== nothing | ||
| error("Option `$flag` does not take a value") | ||
| end | ||
| end |
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I don't think it'd be a bad idea to accept things like --verbose={true,false}, but currently these flags don't accept any value and error badly anyway, at least this gives a nice and clear error message.
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