from unittest.mock import MagicMock
from vllm.config.cache import CacheConfig
from vllm.v1.core.kv_cache_utils import may_override_num_blocks
from vllm.v1.core.block_pool import BlockPool

# Step 1 — CacheConfig silently accepts 0 (and -1).
assert CacheConfig(num_gpu_blocks_override=0).num_gpu_blocks_override == 0
assert CacheConfig(num_gpu_blocks_override=-1).num_gpu_blocks_override == -1

# Step 2 — the override replaces a positive profiled num_blocks.
vllm_cfg = MagicMock()
vllm_cfg.cache_config = CacheConfig(num_gpu_blocks_override=0)
assert may_override_num_blocks(vllm_cfg, num_blocks=4096) == 0

# Step 3 — BlockPool asserts, with no useful message.
BlockPool(num_gpu_blocks=0, enable_caching=False, hash_block_size=16)
# AssertionError                            Traceback (most recent call last)
#   File "vllm/v1/core/block_pool.py", line 157, in __init__
#     assert isinstance(num_gpu_blocks, int) and num_gpu_blocks > 0
# AssertionError

---

ValueError: 1 validation error for CacheConfig
num_gpu_blocks_override
  Input should be greater than 0 [type=greater_than, input_value=0, ...]

---

- num_gpu_blocks_override: int | None = None
+ num_gpu_blocks_override: int | None = Field(default=None, gt=0)