How to use the fusesoc.coremanager.CoreManager function in fusesoc

def test_library_add(caplog):
    import tempfile
    from fusesoc.main import add_library
    from fusesoc.coremanager import CoreManager
    from fusesoc.librarymanager import LibraryManager

    tcf = tempfile.NamedTemporaryFile(mode="w+")
    clone_target = tempfile.mkdtemp(prefix='library_add_')
    library_root = tempfile.mkdtemp(prefix='library_add_')
    conf = Config(file=tcf)
    conf.library_root = library_root
    cm = CoreManager(conf)
    args = Namespace()

    args.name = 'fusesoc-cores'
    args.location = clone_target
    args.config = tcf
    args.no_auto_sync = False
    vars(args)['sync-uri'] = sync_uri

    add_library(cm, args)

    expected = """[library.fusesoc-cores]
location = {}
sync-uri = https://github.com/fusesoc/fusesoc-cores
sync-type = git
auto-sync = true""".format(os.path.abspath(clone_target))

def _get_core(name, has_system=False):
    core = None
    try:
        core = CoreManager().get_core(Vlnv(name))
    except RuntimeError as e:
        pr_err(str(e))
        exit(1)
    except DependencyError as e:
        pr_err("'" + name + "' or any of its dependencies requires '" + e.value + "', but this core was not found")
        exit(1)
    if has_system and not core.backend:
        pr_err("Unable to find .system file for '{}'".format(name))
        exit(1)
    return core

def list_cores(args):
    cores = CoreManager().get_cores()
    print("\nAvailable cores:\n")
    if not cores:
        cores_root = CoreManager().get_cores_root()
        if cores_root:
            pr_err("No cores found in "+':'.join(cores_root))
        else:
            pr_err("cores_root is not defined")
        exit(1)
    maxlen = max(map(len,cores.keys()))
    print('Core'.ljust(maxlen) + '   Cache status')
    print("="*80)
    for name in sorted(cores.keys()):
        core = cores[name]
        print(name.ljust(maxlen) + ' : ' + core.cache_status())

def sim(args):
    core = _get_core(args.system)
    if args.sim:
        sim_name = args.sim[0]
    elif core.simulators:
        sim_name = core.simulators[0]
    else:
        pr_err("No simulator was found in '"+ args.system + "' core description")
        logger.error("No simulator was found in '"+ args.system + "' core description")
        exit(1)
    try:
        CoreManager().tool = sim_name
        sim = _import('simulator', sim_name)(core, export=True)
    except DependencyError as e:
        pr_err("'" + args.system + "' or any of its dependencies requires '" + e.value + "', but this core was not found")
        exit(1)
    except ImportError:
        pr_err("Unknown simulator '{}'".format(sim_name))
        exit(1)
    except RuntimeError as e:
        pr_err(str(e))
        exit(1)
    if (args.testbench):
        sim.toplevel = args.testbench[0]
    else:
        sim.toplevel = sim.system.simulator['toplevel']
    if not args.keep or not os.path.exists(sim.work_root):
        try:

def __init__(self, system):
        config = Config()
        self.system = system
        self.build_root = os.path.join(config.build_root, self.system.sanitized_name)
        self.src_root = os.path.join(self.build_root, 'src')

        self.cm = CoreManager()
        self.cores = self.cm.get_depends(self.system.name)

        self.env = os.environ.copy()
        self.env['BUILD_ROOT'] = os.path.abspath(self.build_root)

        self.plusarg    = {}
        self.vlogparam  = {}
        self.generic    = {}
        self.cmdlinearg = {}

def update(args):
    for root in CoreManager().get_cores_root():
        if os.path.exists(root):
            args = ['-C', root,
                    'config', '--get', 'remote.origin.url']
            repo_root = ""
            try:
                repo_root = subprocess.check_output(['git'] + args).decode("utf-8")
                if repo_root.strip() in [repo[1] for repo in REPOS]:
                    pr_info("Updating '{}'".format(root))
                    args = ['-C', root, 'pull']
                    Launcher('git', args).run()
            except subprocess.CalledProcessError:
                pass

def init_coremanager(config, args_cores_root):
    logger.debug("Initializing core manager")
    cm = CoreManager(config)

    args_libs = [Library(acr, acr) for acr in args_cores_root]
    #Add libraries from config file, env var and command-line
    for library in config.libraries + args_libs:
        try:
            cm.add_library(library)
        except (RuntimeError, IOError) as e:
            _s = "Failed to register library '{}'"
            logger.warning(_s.format(str(e)))

    return cm