def make_fake_index_file(path: str) -> None:
    """Create a fake index file in the path."""
    fake_index = {
        'shards': [{
            'column_encodings': ['bytes'],
            'column_names': ['tokens'],
            'column_sizes': [None],
            'compression': 'zstd',
            'format': 'mds',
            'hashes': [],
            'raw_data': {
                'basename': 'shard.00000.mds',
                'bytes': 5376759,
                'hashes': {},
            },
            'samples': 328,
            'size_limit': 67108864,
            'version': 2,
            'zip_data': {
                'basename': 'shard.00000.mds.zstd',
                'bytes': 564224,
                'hashes': {},
            },
        }],
        'version': 2,
    }
    if not os.path.exists(path):
        os.makedirs(os.path.dirname(path), exist_ok=True)
        with open(path, 'w') as f:
            json.dump(fake_index, f)
Create a fake index file in the path.
tests/a_scripts/train/test_train_inputs.py