pytest-dev/pytest · error · UsageError

Unknown parametrize_long_str_id_strategy

Error message

Unknown parametrize_long_str_id_strategy: {value!r}. Valid values: {', '.join(sorted(_LONG_STR_STRATEGIES))}

What it means

Thrown by Metafunc._get_long_str_strategy() when the ini value `parametrize_long_str_id_strategy` is not one of the recognized literals: 'short', 'sha256', 'legacy', 'disallow'. It guards config typos before they affect parametrize id generation.

Solutions

1. Set the value to one of: short, sha256, legacy, disallow (lowercase, exact).
2. Remove the ini key to fall back to the default ('short').
3. Check for typos and trailing whitespace in the ini value.

Example fix

// before - pytest.ini
[pytest]
parametrize_long_str_id_strategy = SHA-256
// after
[pytest]
parametrize_long_str_id_strategy = sha256

valid = {'short', 'sha256', 'legacy', 'disallow'}
value = config.getini('parametrize_long_str_id_strategy')
if value not in valid:
    raise ValueError(f'bad strategy {value!r}, choose from {sorted(valid)}')

def is_valid_strategy(v: object) -> bool:
    return v in {'short', 'sha256', 'legacy', 'disallow'}

When it happens

Trigger: Setting parametrize_long_str_id_strategy = sha in pytest.ini (truncated); a typo like 'sha-256' or 'SHA256' (case-sensitive); an old config from a pytest version that supported a different value set.

Common situations: Upgrading pytest and finding the strategy name changed; copy-paste from docs with a typo; case mismatch.

Related errors

• error raised while trying to determine id of parameter
• ids must be a callable or an iterable
• ' ' is not recognized as a logging level name for ' '…
• Missing required plugins
• must be a directory, given

AI-assisted analysis of pytest-dev/pytest@0d6fbdeffa (2026-08-11). Data as JSON: /api/errors/4f3bf2b479f55d5a. Report an issue: GitHub.

Appendix: source

Thrown at src/_pytest/python.py:1041

        idval = self._idval_from_hook(val, argname)
        if idval is not None:
            return idval
        if isinstance(val, str | bytes):
            idval = self._apply_long_str_strategy(val, argname, idx)
            if idval is not None:
                return idval
        else:
            idval = self._idval_from_value(val)
            if idval is not None:
                return idval
        return self._idval_from_argname(argname, idx)

    def _get_long_str_strategy(self) -> LongStrIdStrategy:
        if not self.config:
            return "short"
        value = self.config.getini("parametrize_long_str_id_strategy")
        if value not in _LONG_STR_STRATEGIES:
            raise UsageError(
                f"Unknown parametrize_long_str_id_strategy: {value!r}. "
                f"Valid values: {', '.join(sorted(_LONG_STR_STRATEGIES))}"
            )
        return cast(LongStrIdStrategy, value)

    def _apply_long_str_strategy(
        self, val: str | bytes, argname: str, idx: int
    ) -> str | None:
        """Apply the configured strategy for long str/bytes parameter values.

        Only used for auto-generated IDs (not explicit ids=[...] or
        pytest.param(id=...)).
        """
        if len(val) <= 100:
            return _ascii_escaped_by_config(val, self.config)
        match self._get_long_str_strategy():
            case "legacy":
                return _ascii_escaped_by_config(val, self.config)

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