Fix for LazyBlockList refactor. (ray-project#19333)

python/ray/data/tests/test_dataset.py

@@ -1316,17 +1316,17 @@ def test_parquet_read_parallel_meta_fetch(ray_start_regular_shared, fs,
  data_path, filesystem=fs, parallelism=parallelism)
 
  # Test metadata-only parquet ops.
- assert len(ds._blocks._blocks) == 1
+ assert ds._blocks._num_computed() == 1
  assert ds.count() == num_dfs * 3
  assert ds.size_bytes() > 0
  assert ds.schema() is not None
  input_files = ds.input_files()
  assert len(input_files) == num_dfs, input_files
- assert len(ds._blocks._blocks) == 1
+ assert ds._blocks._num_computed() == 1
 
  # Forces a data read.
  values = [s["one"] for s in ds.take(limit=3 * num_dfs)]
- assert len(ds._blocks._blocks) == parallelism
+ assert ds._blocks._num_computed() == parallelism
  assert sorted(values) == list(range(3 * num_dfs))