How to use the wily.cache.exists function in wily

def test_exists_older(tmpdir):
    """
    Test that exists() returns true if path does exist
    and has a file with the version older than the current
    """
    config = DEFAULT_CONFIG
    tmp_path = pathlib.Path(tmpdir)
    config.cache_path = tmp_path / ".wily"
    (tmp_path / ".wily").mkdir()
    with open((tmp_path / ".wily" / "index.json"), "w+") as index:
        index.write('{"version": "0.1.0"}')
    assert cache.exists(config)

def test_not_exists():
    """
    Test that exists() returns false if path does not exist
    """
    config = DEFAULT_CONFIG
    config.cache_path = "/v/v/w"
    assert not cache.exists(config)

def test_clean_when_not_exists(tmpdir):
    """
    Test that clean() will continue if the folder does not exist
    """
    config = DEFAULT_CONFIG
    cache_path = pathlib.Path(tmpdir) / ".wily"
    config.cache_path = str(cache_path)
    assert not cache.exists(config)
    assert cache.clean(config) is None

def test_create_when_exists(tmpdir):
    """
    Test that create() will continue if the folder already exists
    """
    config = DEFAULT_CONFIG
    cache_path = pathlib.Path(tmpdir) / ".wily"
    pathlib.Path(cache_path).mkdir()
    config.cache_path = str(cache_path)
    assert cache.exists(config)
    assert str(cache.create(config)) == str(cache_path)

def test_create_and_delete(tmpdir):
    """
    Test that create() will create a folder with the correct path
    and then delete it.
    """
    config = DEFAULT_CONFIG
    cache_path = pathlib.Path(tmpdir) / ".wily"
    config.cache_path = str(cache_path)
    assert not cache.exists(config)
    cache.create(config)
    assert cache.exists(config)
    cache.clean(config)
    assert not cache.exists(config)

Graph all .py files within src/ for the raw.loc metric

        $ wily graph src/ raw.loc

    Graph test.py against raw.loc and cyclomatic.complexity metrics

        $ wily graph src/test.py raw.loc cyclomatic.complexity

    Graph test.py against raw.loc and raw.sloc on the x-axis

        $ wily graph src/test.py raw.loc --x-axis raw.sloc
    """
    config = ctx.obj["CONFIG"]

    if not exists(config):
        handle_no_cache(ctx)

    from wily.commands.graph import graph

    logger.debug(f"Running report on {path} for metrics {metrics}")
    graph(
        config=config,
        path=path,
        metrics=metrics,
        output=output,
        x_axis=x_axis,
        changes=changes,
    )

def report(ctx, file, metrics, number, message, format, console_format, output):
    """Show metrics for a given file."""
    config = ctx.obj["CONFIG"]

    if not exists(config):
        handle_no_cache(ctx)

    if not metrics:
        metrics = get_default_metrics(config)
        logger.info(f"Using default metrics {metrics}")

    new_output = Path().cwd()
    if output:
        new_output = new_output / Path(output)
    else:
        new_output = new_output / "wily_report" / "index.html"

    from wily.commands.report import report

    logger.debug(f"Running report on {file} for metric {metrics}")
    logger.debug(f"Output format is {format}")