pytest-dev/pytest · error · ValueError

pytester_example_dir is unset, can't copy examples

Error message

pytester_example_dir is unset, can't copy examples

What it means

Thrown by Pytester.copy_example() when the `pytester_example_dir` ini option is not set. copy_example() needs a project-level directory to find example files; without it there is nowhere to copy from.

Solutions

1. Add `pytester_example_dir = example` (or your dir) under [pytest] in pytest.ini / pyproject.toml / tox.ini.
2. If examples live elsewhere, point pytester_example_dir at the correct relative path from rootdir.
3. Skip the test when the ini is unset: pytest.importorskip or a custom skip guard.

Example fix

// before - pytest.ini missing the key
[pytest]
addopts = -ra
// after
[pytest]
addopts = -ra
pytester_example_dir = examples

example_dir = pytester._request.config.getini('pytester_example_dir')
if example_dir is None:
    pytest.skip('pytester_example_dir not configured')
pytester.copy_example()

When it happens

Trigger: Calling pytester.copy_example() in a test where pytest.ini/tox.ini/setup.cfg does not define pytester_example_dir; running tests in a downstream project that reuses your test suite but didn't carry over the ini setting.

Common situations: Copy-pasting a pytester test that uses copy_example into a new project without adding the ini key; upgrading pytest and forgetting that the ini option name must match exactly.

Related errors

• example " " is not found as a file or directory
• can't be found as module or package in
• Unknown parametrize_long_str_id_strategy
• alias conflicts with existing configuration option
• is already an alias of

AI-assisted analysis of pytest-dev/pytest@0d6fbdeffa (2026-08-11). Data as JSON: /api/errors/26e09bd019fc271b. Report an issue: GitHub.

Appendix: source

Thrown at src/_pytest/pytester.py:958

        gets recognised as a Python package.
        """
        p = self.path / name
        p.mkdir()
        p.joinpath("__init__.py").touch()
        return p

    def copy_example(self, name: str | None = None) -> Path:
        """Copy file from project's directory into the testdir.

        :param name:
            The name of the file to copy.
        :return:
            Path to the copied directory (inside ``self.path``).
        :rtype: pathlib.Path
        """
        example_dir_ = self._request.config.getini("pytester_example_dir")
        if example_dir_ is None:
            raise ValueError("pytester_example_dir is unset, can't copy examples")
        example_dir: Path = self._request.config.rootpath / example_dir_

        for extra_element in self._request.node.iter_markers("pytester_example_path"):
            assert extra_element.args
            example_dir = example_dir.joinpath(*extra_element.args)

        if name is None:
            func_name = self._name
            maybe_dir = example_dir / func_name
            maybe_file = example_dir / (func_name + ".py")

            if maybe_dir.is_dir():
                example_path = maybe_dir
            elif maybe_file.is_file():
                example_path = maybe_file
            else:
                raise LookupError(
                    f"{func_name} can't be found as module or package in {example_dir}"

View on GitHub (pinned to 0d6fbdeffa)