def freeze(h, output_yaml, resolve, groups):
    """Output installed packages."""
    if not groups:
        groups = filter(lambda group: not group.lower().startswith("bower"),
                        h.requirements.keys())
    else:
        groups = [text_type.strip(group) for group in groups.split(",")]

    if output_yaml:
        for requirements in h.requirements.values():
            for requirement in requirements:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
        click.echo(h.requirements.yaml)
    else:
        for group in groups:
            if not h.requirements[group]:
                continue
            click.echo("# {}".format(group))
            for requirement in h.requirements[group]:
                if resolve and not requirement.version:
                    requirement.load_installed_version()
                click.echo(str(requirement))
def test_reverse_iso8601_datetime():
    dates = [
        ("2011-01-01T00:00:00+00:00", datetime(2011, 1, 1, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59+00:00", datetime(2011, 1, 1, 23, 59, 59, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59.001000+00:00", datetime(2011, 1, 1, 23, 59, 59, 1000, tzinfo=pytz.utc)),
        ("2011-01-01T23:59:59+02:00", datetime(2011, 1, 1, 21, 59, 59, tzinfo=pytz.utc))
    ]

    for date_string, expected in dates:
        yield assert_equal, inputs.datetime_from_iso8601(date_string), expected