def METHOD_NAME(tmpdir):
    def touch(path: Path) -> None:
        if path.is_dir():
            raise ValueError("Only files, not folders are supported")
        path.parent.mkdir(parents=True, exist_ok=True)
        path.touch()
    def rlist(input_dir):
        """Recursively list files in input_dir"""
        paths = list(sorted(input_dir.rglob("*")))
        res = []
        for el in paths:
            if el.is_file():
                res.append(str(el.relative_to(input_dir)))
        return res
    install_prefix = Path(str(tmpdir / "install"))
    test_install_prefix = Path(str(tmpdir / "install-tests"))
    # create the example package
    touch(install_prefix / "ex1" / "base.py")
    touch(install_prefix / "ex1" / "conftest.py")
    touch(install_prefix / "ex1" / "test_base.py")
    touch(install_prefix / "ex1" / "tests" / "data.csv")
    touch(install_prefix / "ex1" / "tests" / "test_a.py")
    n_moved = buildpkg.unvendor_tests(install_prefix, test_install_prefix)
    assert rlist(install_prefix) == ["ex1/base.py"]
    assert rlist(test_install_prefix) == [
        "ex1/conftest.py",
        "ex1/test_base.py",
        "ex1/tests/data.csv",
        "ex1/tests/test_a.py",
    ]
    # One test folder and two test file
    assert n_moved == 3