def METHOD_NAME(fs):
    fsa = fs
    test_path = os.path.join(BASE_PATH, str(uuid.uuid4()) + '.npy')
    dd = np.random.rand(500, 500)
    with fs_write.NpyWriter(test_path,
                            resource_kwargs={'mmap_mode': 'r'},
                            fs=fs) as f:
        datum_id = f.add_data(dd)
    with fsa.handler_context({'npy': fs_read.NpyHandler}):
        ret = fsa.retrieve(datum_id)
    assert_array_equal(dd, ret)