How to use the twine.package.PackageFile.from_filename function in twine

def test_skip_existing_skips_files_on_repository(response_kwargs):
    assert upload.skip_upload(
        response=pretend.stub(**response_kwargs),
        skip_existing=True,
        package=package_file.PackageFile.from_filename(helpers.WHEEL_FIXTURE, None),
    )

def test_skip_upload_respects_skip_existing():
    assert not upload.skip_upload(
        response=pretend.stub(),
        skip_existing=False,
        package=package_file.PackageFile.from_filename(helpers.WHEEL_FIXTURE, None),
    )

def test_pkginfo_returns_no_metadata(monkeypatch):
    """Raise an exception when pkginfo can't interpret the metadata.

    This could be caused by a version number or format it doesn't support yet.
    """

    def EmptyDist(filename):
        return pretend.stub(name=None, version=None)

    monkeypatch.setattr(package_file, "DIST_TYPES", {"bdist_wheel": EmptyDist})
    filename = "tests/fixtures/twine-1.5.0-py2.py3-none-any.whl"

    with pytest.raises(exceptions.InvalidDistribution) as err:
        package_file.PackageFile.from_filename(filename, comment=None)

    assert "Invalid distribution metadata" in err.value.args[0]

def upload(upload_settings, dists):
    dists = _find_dists(dists)

    # Determine if the user has passed in pre-signed distributions
    signatures = {os.path.basename(d): d for d in dists if d.endswith(".asc")}
    uploads = [i for i in dists if not i.endswith(".asc")]
    upload_settings.check_repository_url()
    repository_url = upload_settings.repository_config['repository']

    print("Uploading distributions to {}".format(repository_url))

    repository = upload_settings.create_repository()
    uploaded_packages = []

    for filename in uploads:
        package = PackageFile.from_filename(filename, upload_settings.comment)
        skip_message = (
            "  Skipping {} because it appears to already exist".format(
                package.basefilename)
        )

        # Note: The skip_existing check *needs* to be first, because otherwise
        #       we're going to generate extra HTTP requests against a hardcoded
        #       URL for no reason.
        if (upload_settings.skip_existing and
                repository.package_is_uploaded(package)):
            print(skip_message)
            continue

        signed_name = package.signed_basefilename
        if signed_name in signatures:
            package.add_gpg_signature(signatures[signed_name], signed_name)