# SPDX-License-Identifier: Apache-2.0

# SPDX-FileCopyrightText: Copyright The Lance Authors

"""Tests for creating empty indices with train=False."""

import lance

import pyarrow as pa

import pyarrow.compute as pc

def test_create_empty_scalar_index():

data = pa.table({"id": range(100)})

dataset = lance.write_dataset(data, "memory://")

# Passing train=False to create an empty index

dataset.create_scalar_index("id", "BTREE", train=False)

# Verify index exists and has correct stats

indices = dataset.list_indices()

assert len(indices) == 1

assert indices[0]["type"] == "BTree"

stats = dataset.stats.index_stats(indices[0]["name"])

assert stats["num_indexed_rows"] == 0

assert stats["num_unindexed_rows"] == dataset.count_rows()

def test_create_empty_vector_index():

dim = 32

values = pc.random(100 * dim).cast(pa.float32())

vectors = pa.FixedSizeListArray.from_arrays(values, dim)

data = pa.table({"vector": vectors})

dataset = lance.write_dataset(data, "memory://")

# Currently, vector indices with train=False are not supported

try:

dataset.create_index(

"vector", "IVF_PQ", num_partitions=10, num_sub_vectors=8, train=False

)

# If we get here, the implementation has been added (unexpected for now)

assert False, (

"Expected NotImplementedError for train=False on vector index, "

"but succeeded"

)

except NotImplementedError as e:

# Expected error for unimplemented functionality

error_msg = str(e).lower()

assert "not yet implemented" in error_msg or "not implemented" in error_msg