pytest-dev/pytest · error · TypeError

{self.inipath}: config option '{name}' expects a string, got

Error message

{self.inipath}: config option '{name}' expects a string, got {builtins.type(value).__name__}: {value!r}

What it means

Raised by Config._getini_value (config/__init__.py:1860-1867) when an ini option is registered with a Literal/choice type (an _IniLiteral carrying .choices) but the value read from config is not a Python str. Literal choices are checked verbatim with no coercion, in both ini and toml modes, so a non-string (e.g. a TOML int) is rejected before the choice membership test.

Source

Thrown at src/_pytest/config/__init__.py:1864

            )
        except (TypeError, ValueError) as e:
            raise UsageError(str(e)) from e

    def _getini_value(
        self,
        mode: Literal["ini", "toml"],
        name: str,
        canonical_name: str,
        type: str | _IniLiteral,
        value: object,
        default: Any,
    ):
        """Convert a config value, read in the given mode, to the option's type."""
        if isinstance(type, _IniLiteral):
            # A Literal value is a plain string checked against the registered
            # choices, without coercion, in both ini and toml modes.
            if not isinstance(value, str):
                raise TypeError(
                    f"{self.inipath}: config option '{name}' expects a string, "
                    f"got {builtins.type(value).__name__}: {value!r}"
                )
            if value not in type.choices:
                raise ValueError(
                    f"{self.inipath}: config option '{name}' expects one of "
                    f"{_ini_type_repr(type)}, got {value!r}"
                )
            return value
        if mode == "ini":
            # In ini mode, values are always str | list[str].
            assert isinstance(value, (str, list))
            return self._getini_ini(name, canonical_name, type, value, default)
        elif mode == "toml":
            return self._getini_toml(name, canonical_name, type, value, default)
        else:
            assert_never(mode)

View on GitHub (pinned to 98b357f69e)

Solutions

Quote the value in TOML so it parses as a string: my_opt = "strict".
Verify the value is one of the documented choices for that option.
If the option legitimately accepts non-string types, the plugin should register a non-Literal type (e.g. 'int').

Example fix

# before (pyproject.toml)
[tool.pytest.ini_options]
log_level = 20   # Literal choice expects a string

# after
log_level = "INFO"

Defensive patterns

Strategy: validation

Validate before calling

def ensure_str_choice(value):
    if not isinstance(value, str):
        raise TypeError(f'choice option must be a string, got {type(value).__name__}')
    return value

Type guard

def is_str_value(value) -> bool:
    return isinstance(value, str)

Try / catch

try:
    config.getini(name)
except Exception:
    # quote the value in pyproject.toml and rerun

Prevention

In TOML, always quote choice option values.
Validate config values programmatically before invoking pytest in CI.
Document the expected native type for each option.

When it happens

Trigger: Registering addini(..., type=..., choices=[...]) and supplying, via TOML, a value of native non-string type (int/bool/list) for that key. getini() or any ini read then trips this branch.

Common situations: pyproject.toml sets a choice option to a bare integer or boolean instead of a quoted string; converting an .ini file to .toml and dropping the quotes; a plugin registering choices but the user supplying the wrong native TOML type.

Related errors

AI-assisted analysis of pytest-dev/pytest@98b357f69e (2026-08-04). Data as JSON: /data/errors/8587a2c455b25ae2.json. Report an issue: GitHub.