def download_file(url, dest=None, chunk_size=1024, replace="ask",
                  label="Downloading {dest_basename} ({size:.2f}MB)",
                  expected_extension=None):
    """Download a file from a given URL and display progress.

    :param dest: If the destination exists and is a directory, the filename
        will be guessed from the Content-Disposition header. If the destination
        is an existing file, the user will either be prompted to overwrite, or
        the file will be replaced (depending on the value of **replace**). If
        the destination does not exist, it will be used as the filename.
    :param int chunk_size: bytes read in at a time.
    :param replace: If `False`, an existing destination file will not be
        overwritten.
    :param label: a string which is formatted and displayed as the progress bar
        label. Variables provided include *dest_basename*, *dest*, and *size*.
    :param expected_extension: if set, the filename will be sanitized to ensure
        it has the given extension. The extension should not start with a dot
        (`.`).
    """
    dest = Path(dest or url.split("/")[-1])
    response = get(url, stream=True)
    if (dest.exists()
            and dest.is_dir()
            and "Content-Disposition" in response.headers):
        content_disposition = rfc6266.parse_requests_response(response)
        if expected_extension is not None:
            filename = content_disposition.filename_sanitized(
                expected_extension)
        filename = secure_filename(filename)
        dest = dest / filename
    if dest.exists() and not dest.is_dir():
        if (replace is False
                or replace == "ask"
                and not click.confirm("Replace {}?".format(dest))):
            return str(dest)
    size = int(response.headers.get("content-length", 0))
    label = label.format(dest=dest, dest_basename=dest.name,
                         size=size/1024.0/1024)
    with click.open_file(str(dest), "wb") as f:
        content_iter = response.iter_content(chunk_size=chunk_size)
        with click.progressbar(content_iter, length=size/1024,
                               label=label) as bar:
            for chunk in bar:
                if chunk:
                    f.write(chunk)
                    f.flush()
    return str(dest)
def test_isointerval():
    intervals = [
        (
            # Full precision with explicit UTC.
            "2013-01-01T12:30:00Z/P1Y2M3DT4H5M6S",
            (
                datetime(2013, 1, 1, 12, 30, 0, tzinfo=pytz.utc),
                datetime(2014, 3, 5, 16, 35, 6, tzinfo=pytz.utc),
            ),
        ),
        (
            # Full precision with alternate UTC indication
            "2013-01-01T12:30+00:00/P2D",
            (
                datetime(2013, 1, 1, 12, 30, 0, tzinfo=pytz.utc),
                datetime(2013, 1, 3, 12, 30, 0, tzinfo=pytz.utc),
            ),
        ),
        (
            # Implicit UTC with time
            "2013-01-01T15:00/P1M",
            (
                datetime(2013, 1, 1, 15, 0, 0, tzinfo=pytz.utc),
                datetime(2013, 1, 31, 15, 0, 0, tzinfo=pytz.utc),
            ),
        ),
        (
            # TZ conversion
            "2013-01-01T17:00-05:00/P2W",
            (
                datetime(2013, 1, 1, 22, 0, 0, tzinfo=pytz.utc),
                datetime(2013, 1, 15, 22, 0, 0, tzinfo=pytz.utc),
            ),
        ),
        (
            # Date upgrade to midnight-midnight period
            "2013-01-01/P3D",
            (
                datetime(2013, 1, 1, 0, 0, 0, tzinfo=pytz.utc),
                datetime(2013, 1, 4, 0, 0, 0, 0, tzinfo=pytz.utc),
            ),
        ),
        (
            # Start/end with UTC
            "2013-01-01T12:00:00Z/2013-02-01T12:00:00Z",
            (
                datetime(2013, 1, 1, 12, 0, 0, tzinfo=pytz.utc),
                datetime(2013, 2, 1, 12, 0, 0, tzinfo=pytz.utc),
            ),
        ),
        (
            # Start/end with time upgrade
            "2013-01-01/2013-06-30",
            (
                datetime(2013, 1, 1, tzinfo=pytz.utc),
                datetime(2013, 6, 30, tzinfo=pytz.utc),
            ),
        ),
        (
            # Start/end with TZ conversion
            "2013-02-17T12:00:00-07:00/2013-02-28T15:00:00-07:00",
            (
                datetime(2013, 2, 17, 19, 0, 0, tzinfo=pytz.utc),
                datetime(2013, 2, 28, 22, 0, 0, tzinfo=pytz.utc),
            ),
        ),
        # Resolution expansion for single date(time)
        (
            # Second with UTC
            "2013-01-01T12:30:45Z",
            (
                datetime(2013, 1, 1, 12, 30, 45, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 12, 30, 46, tzinfo=pytz.utc),
            ),
        ),
        (
            # Second with tz conversion
            "2013-01-01T12:30:45+02:00",
            (
                datetime(2013, 1, 1, 10, 30, 45, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 10, 30, 46, tzinfo=pytz.utc),
            ),
        ),
        (
            # Second with implicit UTC
            "2013-01-01T12:30:45",
            (
                datetime(2013, 1, 1, 12, 30, 45, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 12, 30, 46, tzinfo=pytz.utc),
            ),
        ),
        (
            # Minute with UTC
            "2013-01-01T12:30+00:00",
            (
                datetime(2013, 1, 1, 12, 30, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 12, 31, tzinfo=pytz.utc),
            ),
        ),
        (
            # Minute with conversion
            "2013-01-01T12:30+04:00",
            (
                datetime(2013, 1, 1, 8, 30, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 8, 31, tzinfo=pytz.utc),
            ),
        ),
        (
            # Minute with implicit UTC
            "2013-01-01T12:30",
            (
                datetime(2013, 1, 1, 12, 30, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 12, 31, tzinfo=pytz.utc),
            ),
        ),
        (
            # Hour, explicit UTC
            "2013-01-01T12Z",
            (
                datetime(2013, 1, 1, 12, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 13, tzinfo=pytz.utc),
            ),
        ),
        (
            # Hour with offset
            "2013-01-01T12-07:00",
            (
                datetime(2013, 1, 1, 19, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 20, tzinfo=pytz.utc),
            ),
        ),
        (
            # Hour with implicit UTC
            "2013-01-01T12",
            (
                datetime(2013, 1, 1, 12, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 13, tzinfo=pytz.utc),
            ),
        ),
        (
            # Interval with trailing zero fractional seconds should
            # be accepted.
            "2013-01-01T12:00:00.0/2013-01-01T12:30:00.000000",
            (
                datetime(2013, 1, 1, 12, tzinfo=pytz.utc),
                datetime(2013, 1, 1, 12, 30, tzinfo=pytz.utc),
            ),
        ),
    ]

    for value, expected in intervals:
        yield assert_equal, inputs.iso8601interval(value), expected