[Misc] Fix `Current vLLM config is not set.` warnings, assert to avoid issues...

[Misc] Fix `Current vLLM config is not set.` warnings, assert to avoid issues in the future (#31747)
Signed-off-by: Lucas Wilkinson <lwilkins@redhat.com>
Signed-off-by: Lucas Wilkinson <LucasWilkinson@users.noreply.github.com>
Co-authored-by: Luka Govedič <ProExpertProg@users.noreply.github.com>

tests/lora/test_lora_manager.py

@@ -111,7 +111,7 @@ def create_packed_lora(
     return LoRAModel(lora_id, 8, loras)
 
 
-def test_replace_submodules(dist_init, dummy_model):
+def test_replace_submodules(default_vllm_config, dist_init, dummy_model):
     model = dummy_model
     manager = LoRAModelManager(
         model,
@@ -133,7 +133,7 @@ def test_replace_submodules(dist_init, dummy_model):
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_lora_model_manager(dist_init, dummy_model, device):
+def test_lora_model_manager(default_vllm_config, dist_init, dummy_model, device):
     model = dummy_model
     model_lora1 = create_lora(
         1, model, ["layer1.dense1", "dense2", "lm_head"], device=device
@@ -199,7 +199,9 @@ def test_lora_model_manager(dist_init, dummy_model, device):
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_lora_lru_cache_model_manager(dist_init, dummy_model, device):
+def test_lora_lru_cache_model_manager(
+    default_vllm_config, dist_init, dummy_model, device
+):
     model = dummy_model
     model_lora1 = create_lora(
         1, model, ["layer1.dense1", "dense2", "lm_head"], device=device
@@ -289,7 +291,7 @@ def test_lora_lru_cache_model_manager(dist_init, dummy_model, device):
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_lru_lora_model_manager(dist_init, dummy_model, device):
+def test_lru_lora_model_manager(default_vllm_config, dist_init, dummy_model, device):
     # This tests just the LRU cache functionality, everything else is
     # tested in test_lora_model_manager
     model = dummy_model
@@ -415,7 +417,9 @@ def test_lru_lora_model_manager(dist_init, dummy_model, device):
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_lru_cache_worker_adapter_manager(dist_init, dummy_model, device, tmp_path):
+def test_lru_cache_worker_adapter_manager(
+    default_vllm_config, dist_init, dummy_model, device, tmp_path
+):
     lora_config = LoRAConfig(
         max_lora_rank=8, max_cpu_loras=4, max_loras=4, lora_dtype=DEFAULT_DTYPE
     )
@@ -529,7 +533,9 @@ def test_lru_cache_worker_adapter_manager(dist_init, dummy_model, device, tmp_pa
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_worker_adapter_manager(dist_init, dummy_model_gate_up, device, tmp_path):
+def test_worker_adapter_manager(
+    default_vllm_config, dist_init, dummy_model_gate_up, device, tmp_path
+):
     # Should remove every LoRA not specified in the request.
     lora_config = LoRAConfig(
         max_lora_rank=8, max_cpu_loras=4, max_loras=4, lora_dtype=DEFAULT_DTYPE
@@ -636,7 +642,7 @@ def test_worker_adapter_manager(dist_init, dummy_model_gate_up, device, tmp_path
 
 
 @pytest.mark.parametrize("device", DEVICES)
-def test_packed_loras(dist_init, dummy_model_gate_up, device):
+def test_packed_loras(default_vllm_config, dist_init, dummy_model_gate_up, device):
     model = dummy_model_gate_up
     model_lora = create_packed_lora(
         1,

tests/model_executor/test_eagle_quantization.py

@@ -55,7 +55,7 @@ def test_get_draft_quant_config_without_draft_model():
 
 @torch.inference_mode()
 @pytest.mark.parametrize("device", DEVICES)
-def test_fc_layer_quant_config_usage(dist_init, device) -> None:
+def test_fc_layer_quant_config_usage(default_vllm_config, dist_init, device) -> None:
     import torch
 
     from vllm.model_executor.layers.linear import ReplicatedLinear

tests/models/multimodal/pooling/test_intern_vit.py

@@ -73,7 +73,9 @@ def run_intern_vit_test(
     ],
 )
 @pytest.mark.parametrize("dtype", ["half"])
-def test_models(dist_init, image_assets, model_id, dtype: str) -> None:
+def test_models(
+    default_vllm_config, dist_init, image_assets, model_id, dtype: str
+) -> None:
     run_intern_vit_test(
         image_assets,
         model_id,

tests/models/multimodal/pooling/test_radio.py

@@ -92,7 +92,9 @@ def run_radio_test(
     ],
 )
 @pytest.mark.parametrize("dtype", ["half", "bfloat16"])
-def test_radio(dist_init, image_assets, model_id, dtype: str) -> None:
+def test_radio(
+    default_vllm_config, dist_init, image_assets, model_id, dtype: str
+) -> None:
     run_radio_test(
         image_assets,
         model_id,

tests/models/multimodal/processing/test_tensor_schema.py

@@ -145,18 +145,18 @@ def initialize_dummy_model(
     model_config: ModelConfig,
 ):
     temp_file = tempfile.mkstemp()[1]
-    init_distributed_environment(
-        world_size=1,
-        rank=0,
-        distributed_init_method=f"file://{temp_file}",
-        local_rank=0,
-        backend="nccl",
-    )
-    initialize_model_parallel(tensor_model_parallel_size=1)
-
     current_device = torch.get_default_device()
     vllm_config = VllmConfig(model_config=model_config)
     with set_current_vllm_config(vllm_config=vllm_config):
+        init_distributed_environment(
+            world_size=1,
+            rank=0,
+            distributed_init_method=f"file://{temp_file}",
+            local_rank=0,
+            backend="nccl",
+        )
+        initialize_model_parallel(tensor_model_parallel_size=1)
+
         with set_default_torch_dtype(model_config.dtype):
             torch.set_default_device(current_platform.device_type)
             model = model_cls(vllm_config=vllm_config)

tests/plugins_tests/test_platform_plugins.py

@@ -31,7 +31,7 @@ def test_platform_plugins():
     )
 
 
-def test_oot_custom_op(monkeypatch: pytest.MonkeyPatch):
+def test_oot_custom_op(default_vllm_config, monkeypatch: pytest.MonkeyPatch):
     # simulate workload by running an example
     load_general_plugins()
     from vllm.model_executor.layers.rotary_embedding import RotaryEmbedding

tests/quantization/test_fp8.py

@@ -277,6 +277,7 @@ def test_scaled_fp8_quant(dtype) -> None:
 # this is the case for marlin as well as per-tensor Fp8MoEMethod
 @pytest.mark.parametrize("use_marlin", [False])  # skip True
 def test_fp8_reloading(
+    default_vllm_config,
     method_cls,
     is_checkpoint_fp8_serialized,
     weight_block_size,

tests/utils.py

@@ -721,13 +721,34 @@ def init_test_distributed_environment(
     distributed_init_port: str,
     local_rank: int = -1,
 ) -> None:
-    distributed_init_method = f"tcp://localhost:{distributed_init_port}"
-    init_distributed_environment(
-        world_size=pp_size * tp_size,
-        rank=rank,
-        distributed_init_method=distributed_init_method,
-        local_rank=local_rank,
+    # Note: This function is often called from Ray worker processes, so we
+    # can't rely on pytest fixtures to set the config. We check if the config
+    # is already set and only create a default one if needed.
+    from vllm.config import (
+        VllmConfig,
+        get_current_vllm_config_or_none,
+        set_current_vllm_config,
     )
+
+    distributed_init_method = f"tcp://localhost:{distributed_init_port}"
+
+    if get_current_vllm_config_or_none() is not None:
+        # Config already set, use it directly
+        init_distributed_environment(
+            world_size=pp_size * tp_size,
+            rank=rank,
+            distributed_init_method=distributed_init_method,
+            local_rank=local_rank,
+        )
+    else:
+        # No config set, create a default one for the test
+        with set_current_vllm_config(VllmConfig()):
+            init_distributed_environment(
+                world_size=pp_size * tp_size,
+                rank=rank,
+                distributed_init_method=distributed_init_method,
+                local_rank=local_rank,
+            )
     ensure_model_parallel_initialized(tp_size, pp_size)
 
 

tests/v1/attention/test_attention_backends.py

@@ -556,7 +556,7 @@ def _test_backend_correctness(
 @pytest.mark.parametrize("model", ["meta-llama/Meta-Llama-3-8B"])
 @pytest.mark.parametrize("tensor_parallel_size", [1, 2, 4])
 def test_causal_backend_correctness(
-    batch_spec_name: str, model: str, tensor_parallel_size: int
+    default_vllm_config, batch_spec_name: str, model: str, tensor_parallel_size: int
 ):
     """Test backend's correctness with causal attention."""
 

tests/v1/attention/test_attention_backends_selection.py

@@ -79,7 +79,12 @@ from vllm.v1.attention.backends.short_conv_attn import ShortConvAttentionBackend
     ],
 )
 def test_mamba_layers_get_attn_backend(
-    dist_init, layer_class, init_kwargs, expected_backend, expected_mamba_type
+    default_vllm_config,
+    dist_init,
+    layer_class,
+    init_kwargs,
+    expected_backend,
+    expected_mamba_type,
 ):
     """Test that Mamba-like layers return the correct attention backend."""
     layer = layer_class(**init_kwargs)

tests/v1/attention/test_mla_backends.py

@@ -394,7 +394,11 @@ def run_attention_backend(
 @pytest.mark.parametrize("model", ["deepseek-ai/DeepSeek-R1"])
 @pytest.mark.parametrize("tensor_parallel_size", [1, 4, 8, 16])
 def test_backend_correctness(
-    dist_init, batch_spec_name: str, model: str, tensor_parallel_size: int
+    default_vllm_config,
+    dist_init,
+    batch_spec_name: str,
+    model: str,
+    tensor_parallel_size: int,
 ):
     """
     Test that all backends produce similar outputs to a reference implementation

tests/v1/attention/test_sparse_mla_backends.py

@@ -124,7 +124,12 @@ def _quantize_dequantize_fp8_ds_mla(
     reason="FlashMLASparseBackend requires CUDA 9.0 or higher",
 )
 def test_sparse_backend_decode_correctness(
-    dist_init, batch_name, kv_cache_dtype, tensor_parallel_size, workspace_init
+    default_vllm_config,
+    dist_init,
+    batch_name,
+    kv_cache_dtype,
+    tensor_parallel_size,
+    workspace_init,
 ):
     if current_platform.is_rocm():
         pytest.skip("ROCm does not support fp8_ds_mla data type for kv cache.")

tests/v1/determinism/test_rms_norm_batch_invariant.py

@@ -21,7 +21,11 @@ from vllm.model_executor.layers.layernorm import RMSNorm
 @pytest.mark.parametrize("dtype", [torch.float16, torch.bfloat16])
 @pytest.mark.parametrize("eps", [1e-6, 1e-5])
 def test_rms_norm_batch_invariant_vs_standard(
-    batch_size: int, hidden_size: int, dtype: torch.dtype, eps: float
+    default_vllm_config,
+    batch_size: int,
+    hidden_size: int,
+    dtype: torch.dtype,
+    eps: float,
 ):
     """
     Compare batch-invariant Triton RMS norm against standard CUDA implementation.
@@ -68,7 +72,9 @@ def test_rms_norm_batch_invariant_vs_standard(
 @pytest.mark.parametrize("batch_size", [1, 16, 128])
 @pytest.mark.parametrize("seq_len", [1, 32, 512])
 @pytest.mark.parametrize("hidden_size", [2048, 4096])
-def test_rms_norm_3d_input(batch_size: int, seq_len: int, hidden_size: int):
+def test_rms_norm_3d_input(
+    default_vllm_config, batch_size: int, seq_len: int, hidden_size: int
+):
     """
     Test RMS norm with 3D input tensors (batch, seq_len, hidden_size).
 
@@ -107,7 +113,7 @@ def test_rms_norm_3d_input(batch_size: int, seq_len: int, hidden_size: int):
 
 
 @skip_unsupported
-def test_rms_norm_numerical_stability():
+def test_rms_norm_numerical_stability(default_vllm_config):
     """
     Test RMS norm numerical stability with extreme values.
 
@@ -167,7 +173,7 @@ def test_rms_norm_numerical_stability():
 
 
 @skip_unsupported
-def test_rms_norm_formula():
+def test_rms_norm_formula(default_vllm_config):
     """
     Test that RMS norm follows the correct mathematical formula.
 
@@ -201,7 +207,7 @@ def test_rms_norm_formula():
 
 @skip_unsupported
 @pytest.mark.parametrize("hidden_size", [128, 1024, 4096, 16384])
-def test_rms_norm_different_hidden_sizes(hidden_size: int):
+def test_rms_norm_different_hidden_sizes(default_vllm_config, hidden_size: int):
     """
     Test RMS norm with various hidden sizes to ensure block size handling.
 
@@ -238,7 +244,7 @@ def test_rms_norm_different_hidden_sizes(hidden_size: int):
 
 
 @skip_unsupported
-def test_rms_norm_determinism():
+def test_rms_norm_determinism(default_vllm_config):
     """
     Test that batch-invariant RMS norm produces deterministic results.
 

tests/v1/kv_connector/unit/test_nixl_connector.py

@@ -299,6 +299,7 @@ def test_prompt_less_than_block_size():
 )
 def test_kv_transfer_handshake(dist_init):
     """Unit test for basic NixlConnector interface functionality."""
+    from vllm.config import set_current_vllm_config
 
     # Test setup, we creates a scheduler that contains a NixlConnector
     # of role SCHEDULER, and expect it to be serving NixlAgentMetadata from
@@ -308,81 +309,82 @@ def test_kv_transfer_handshake(dist_init):
     vllm_config.kv_transfer_config.kv_buffer_device = "cpu"
     scheduler = create_scheduler(vllm_config)
 
-    # Create two NixlConnector of role WORKER, one is the worker of
-    # the scheduler (prefill), the other is a worker of decode instance.
+    with set_current_vllm_config(vllm_config):
+        # Create two NixlConnector of role WORKER, one is the worker of
+        # the scheduler (prefill), the other is a worker of decode instance.
 
-    # Prefill connector will register KV cache to populate proper handshake
-    # metadata.
-    prefill_connector = NixlConnector(vllm_config, KVConnectorRole.WORKER)
-    kv_cache_shape = FlashAttentionBackend.get_kv_cache_shape(
-        num_blocks=2, block_size=16, num_kv_heads=4, head_size=64
-    )
-    shared_tensor = torch.zeros(*kv_cache_shape, dtype=torch.float16)
-    unique_tensor = torch.zeros(*kv_cache_shape, dtype=torch.float16)
-    kv_caches = {
-        "layer0": shared_tensor,
-        "layer1": unique_tensor,
-        "layer2": shared_tensor,
-    }
-    prefill_connector.register_kv_caches(kv_caches)
-
-    # Simulate EngineCore initialization that would gather connector
-    # metadata from all workers
-    metadata = prefill_connector.get_handshake_metadata()
-
-    # metadata is a NixlHandshakePayload, decode it to get NixlAgentMetadata
-    decoder = msgspec.msgpack.Decoder(NixlAgentMetadata)
-    expected_agent_metadata = decoder.decode(metadata.agent_metadata_bytes)
-
-    # The scheduler connector expects metadata to be in
-    # dict[int, KVConnectorHandshakeMetadata], where the first key is
-    # the dp_rank, the second key is the tp_rank.
-    scheduler_connector = scheduler.get_kv_connector()
-    scheduler_connector.set_xfer_handshake_metadata({0: metadata})
-
-    # Simulate a request that finishes prefill, which returns
-    # corresponding NixlConnectorMetadata for decode instance.
-    BLOCK_SIZE = vllm_config.cache_config.block_size
-    NUM_EXTERNAL_FULL_BLOCKS = 2
-    NUM_TOKENS = int(BLOCK_SIZE * (NUM_EXTERNAL_FULL_BLOCKS + 0.5))
-
-    request = create_request(
-        request_id=1,
-        block_size=BLOCK_SIZE,
-        num_tokens=NUM_TOKENS,
-        do_remote_decode=True,
-    )
-    request.status = RequestStatus.FINISHED_LENGTH_CAPPED
-    delay, kv_connector_metadata = scheduler.get_kv_connector().request_finished(
-        request, [0, 1, 2]
-    )
-    assert delay
-
-    # Decode connector will be able to create handshake with the prefill connector.
-    decode_connector = NixlConnector(vllm_config, KVConnectorRole.WORKER)
-
-    # Here we are testing the retrieval of NIXLAgentMetadata.
-    # Knowing the implementation detail, we override the add_remote_agent
-    # to validate the metadata received is the same as the one in prefill_connector.
-    with patch.object(
-        decode_connector.connector_worker, "add_remote_agent"
-    ) as mock_add_remote_agent:
-        mock_add_remote_agent.return_type = "remote_agent"
-
-        decode_connector.connector_worker._nixl_handshake(
-            kv_connector_metadata["remote_host"],
-            kv_connector_metadata["remote_port"],
-            kv_connector_metadata["tp_size"],
-            kv_connector_metadata["remote_engine_id"],
+        # Prefill connector will register KV cache to populate proper handshake
+        # metadata.
+        prefill_connector = NixlConnector(vllm_config, KVConnectorRole.WORKER)
+        kv_cache_shape = FlashAttentionBackend.get_kv_cache_shape(
+            num_blocks=2, block_size=16, num_kv_heads=4, head_size=64
         )
+        shared_tensor = torch.zeros(*kv_cache_shape, dtype=torch.float16)
+        unique_tensor = torch.zeros(*kv_cache_shape, dtype=torch.float16)
+        kv_caches = {
+            "layer0": shared_tensor,
+            "layer1": unique_tensor,
+            "layer2": shared_tensor,
+        }
+        prefill_connector.register_kv_caches(kv_caches)
+
+        # Simulate EngineCore initialization that would gather connector
+        # metadata from all workers
+        metadata = prefill_connector.get_handshake_metadata()
+
+        # metadata is a NixlHandshakePayload, decode it to get NixlAgentMetadata
+        decoder = msgspec.msgpack.Decoder(NixlAgentMetadata)
+        expected_agent_metadata = decoder.decode(metadata.agent_metadata_bytes)
+
+        # The scheduler connector expects metadata to be in
+        # dict[int, KVConnectorHandshakeMetadata], where the first key is
+        # the dp_rank, the second key is the tp_rank.
+        scheduler_connector = scheduler.get_kv_connector()
+        scheduler_connector.set_xfer_handshake_metadata({0: metadata})
+
+        # Simulate a request that finishes prefill, which returns
+        # corresponding NixlConnectorMetadata for decode instance.
+        BLOCK_SIZE = vllm_config.cache_config.block_size
+        NUM_EXTERNAL_FULL_BLOCKS = 2
+        NUM_TOKENS = int(BLOCK_SIZE * (NUM_EXTERNAL_FULL_BLOCKS + 0.5))
+
+        request = create_request(
+            request_id=1,
+            block_size=BLOCK_SIZE,
+            num_tokens=NUM_TOKENS,
+            do_remote_decode=True,
+        )
+        request.status = RequestStatus.FINISHED_LENGTH_CAPPED
+        delay, kv_connector_metadata = scheduler.get_kv_connector().request_finished(
+            request, [0, 1, 2]
+        )
+        assert delay
+
+        # Decode connector will be able to create handshake with the prefill connector.
+        decode_connector = NixlConnector(vllm_config, KVConnectorRole.WORKER)
+
+        # Here we are testing the retrieval of NIXLAgentMetadata.
+        # Knowing the implementation detail, we override the add_remote_agent
+        # to validate the metadata received is the same as the one in prefill_connector.
+        with patch.object(
+            decode_connector.connector_worker, "add_remote_agent"
+        ) as mock_add_remote_agent:
+            mock_add_remote_agent.return_type = "remote_agent"
+
+            decode_connector.connector_worker._nixl_handshake(
+                kv_connector_metadata["remote_host"],
+                kv_connector_metadata["remote_port"],
+                kv_connector_metadata["tp_size"],
+                kv_connector_metadata["remote_engine_id"],
+            )
 
-        received_metadata = mock_add_remote_agent.call_args.args
-        assert received_metadata[0] == expected_agent_metadata
-        assert received_metadata[1] == 0  # remote_tp_rank
-        assert received_metadata[2] == 1  # remote_tp_size
+            received_metadata = mock_add_remote_agent.call_args.args
+            assert received_metadata[0] == expected_agent_metadata
+            assert received_metadata[1] == 0  # remote_tp_rank
+            assert received_metadata[2] == 1  # remote_tp_size
 
-    # Need to shutdown the background thread to release NIXL side channel port
-    scheduler_connector.shutdown()
+        # Need to shutdown the background thread to release NIXL side channel port
+        scheduler_connector.shutdown()
 
 
 class FakeNixlConnectorWorker(NixlConnectorWorker):
@@ -458,6 +460,7 @@ class TestNixlHandshake:
     )
     def test_multi_xfer_one_engine(
         self,
+        default_vllm_config,
         # dist_init is a fixture that initializes the distributed environment.
         dist_init,
     ):
@@ -547,6 +550,7 @@ class TestNixlHandshake:
     )
     def test_async_load_kv(
         self,
+        default_vllm_config,
         # Fixture that initializes the distributed environment.
         dist_init,
         # Simulate consumer-producer TP sizes.
@@ -605,7 +609,7 @@ class TestNixlHandshake:
     )
     @pytest.mark.parametrize("local_tp_size", [1, 2])
     def test_prefill_tp_size_greater_than_decode_tp_size(
-        self, local_tp_size: int, dist_init
+        self, local_tp_size: int, default_vllm_config, dist_init
     ):
         """
         Verify remote TP > local TP handshake succeeds with different
@@ -670,7 +674,7 @@ class TestNixlHandshake:
     )
     @pytest.mark.parametrize("local_tp_size", [1, 2])
     def test_prefill_tp_size_greater_than_decode_tp_size_mla(
-        self, local_tp_size: int, dist_init
+        self, local_tp_size: int, default_vllm_config, dist_init
     ):
         """
         Verify remote TP > local TP handshake succeeds with different
@@ -770,6 +774,7 @@ class TestNixlHandshake:
     )
     def test_concurrent_load_kv(
         self,
+        default_vllm_config,
         # dist_init is a fixture that initializes the distributed environment.
         dist_init,
     ):
@@ -830,7 +835,9 @@ class TestNixlHandshake:
         "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
         FakeNixlWrapper,
     )
-    def test_handshake_fails_on_kv_cache_layout_mismatch(self, dist_init):
+    def test_handshake_fails_on_kv_cache_layout_mismatch(
+        self, default_vllm_config, dist_init
+    ):
         """
         Verify that adding a remote agent fails if kv_cache_layout differs.
         This test is only relevant for heterogeneous TP.
@@ -879,7 +886,7 @@ class TestNixlHandshake:
         FakeNixlWrapper,
     )
     def test_handshake_succeed_on_kv_cache_layout_mismatch_with_experimental(
-        self, dist_init
+        self, default_vllm_config, dist_init
     ):
         """
         Verify that adding a remote agent fails if kv_cache_layout differs.
@@ -934,7 +941,7 @@ class TestNixlHandshake:
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FakeNixlWrapper,
 )
-def test_kv_connector_stats(dist_init):
+def test_kv_connector_stats(default_vllm_config, dist_init):
     """Test that KV transfer stats are properly recorded and retrieved."""
     vllm_config = create_vllm_config()
 
@@ -1357,7 +1364,7 @@ def _run_abort_timeout_test(llm: LLM, timeout: int):
         "TRITON_ATTN",
     ],
 )
-def test_register_kv_caches(dist_init, attn_backend):
+def test_register_kv_caches(default_vllm_config, dist_init, attn_backend):
     """
     Test that register_kv_caches() properly calls nixl_wrapper methods with
     correct data.
@@ -1518,7 +1525,9 @@ class FakePlatform(Platform):
         ("oot", "VRAM"),
     ],
 )
-def test_kv_buffer_to_nixl_memory_types(dist_init, kv_buffer_device, nixl_memory_type):
+def test_kv_buffer_to_nixl_memory_types(
+    default_vllm_config, dist_init, kv_buffer_device, nixl_memory_type
+):
     """
     Test that register_kv_caches() passes the correct memory types from the
     config to the nixl_wrapper.
@@ -1563,7 +1572,7 @@ def test_kv_buffer_to_nixl_memory_types(dist_init, kv_buffer_device, nixl_memory
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FakeNixlWrapper,
 )
-def test_shutdown_cleans_up_resources(dist_init):
+def test_shutdown_cleans_up_resources(default_vllm_config, dist_init):
     """Test that shutdown() properly cleans up all resources."""
     vllm_config = create_vllm_config()
 
@@ -1622,7 +1631,7 @@ def test_shutdown_cleans_up_resources(dist_init):
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FakeNixlWrapper,
 )
-def test_aborted_request_removed_from_worker_in_batch(dist_init):
+def test_aborted_request_removed_from_worker_in_batch(default_vllm_config, dist_init):
     """
     Create and schedule a request so that P adds it to in-batch tracking via
     the real scheduler, then simulate an abort (request not in next scheduler
@@ -1731,7 +1740,7 @@ class FailingNixlWrapper(FakeNixlWrapper):
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FailingNixlWrapper,
 )
-def test_handshake_failure_returns_finished(dist_init):
+def test_handshake_failure_returns_finished(default_vllm_config, dist_init):
     """Test that handshake failures mark blocks invalid and return via get_finished."""
     vllm_config = create_vllm_config()
 
@@ -1780,7 +1789,7 @@ def test_handshake_failure_returns_finished(dist_init):
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FailingNixlWrapper,
 )
-def test_transfer_setup_failure_returns_finished(dist_init):
+def test_transfer_setup_failure_returns_finished(default_vllm_config, dist_init):
     """Test that transfer setup failures mark blocks invalid
     and return via get_finished."""
     vllm_config = create_vllm_config()
@@ -1855,6 +1864,7 @@ def test_transfer_setup_failure_returns_finished(dist_init):
     FakeNixlWrapper,
 )
 def test_compatibility_hash_validation(
+    default_vllm_config,
     dist_init,
     mismatch_type,
     config_overrides,
@@ -1967,7 +1977,7 @@ def test_compatibility_hash_validation(
     "vllm.distributed.kv_transfer.kv_connector.v1.nixl_connector.NixlWrapper",
     FakeNixlWrapper,
 )
-def test_handshake_decode_errors(dist_init, error_scenario):
+def test_handshake_decode_errors(default_vllm_config, dist_init, error_scenario):
     """
     Test that msgspec decode errors are properly handled during handshake.
 

tests/v1/kv_offload/test_cpu_gpu.py

@@ -50,6 +50,7 @@ NUM_MAPPINGS = [3]
 @pytest.mark.parametrize("device", CUDA_DEVICES)
 @torch.inference_mode()
 def test_transfer(
+    default_vllm_config,
     gpu_to_cpu: bool,
     num_mappings: int,
     head_size: int,

tests/v1/worker/test_gpu_model_runner.py

@@ -112,15 +112,16 @@ def get_vllm_config():
 @pytest.fixture
 def model_runner():
     vllm_config = get_vllm_config()
-    model_config = vllm_config.model_config
-    num_heads = model_config.get_num_kv_heads(vllm_config.parallel_config)
-    head_size = model_config.get_head_size()
-    vllm_config.compilation_config.static_forward_context["layer.0"] = Attention(
-        num_heads, head_size, 0.1
-    )
-    runner = GPUModelRunner(vllm_config, DEVICE)
-    initialize_kv_cache(runner)
-    return runner
+    with set_current_vllm_config(vllm_config):
+        model_config = vllm_config.model_config
+        num_heads = model_config.get_num_kv_heads(vllm_config.parallel_config)
+        head_size = model_config.get_head_size()
+        vllm_config.compilation_config.static_forward_context["layer.0"] = Attention(
+            num_heads, head_size, 0.1
+        )
+        runner = GPUModelRunner(vllm_config, DEVICE)
+        initialize_kv_cache(runner)
+        yield runner
 
 
 model_runner_2 = model_runner
@@ -546,7 +547,7 @@ def test_reload_weights_before_load_model(model_runner):
         model_runner.reload_weights()
 
 
-def test_init_kv_cache_with_kv_sharing_invalid_target_layer_order():
+def test_init_kv_cache_with_kv_sharing_invalid_target_layer_order(default_vllm_config):
     torch.set_default_dtype(torch.float16)
     layer_0 = "model.layers.0.self_attn.attn"
     layer_1 = "model.layers.1.self_attn.attn"
@@ -573,7 +574,7 @@ def test_init_kv_cache_with_kv_sharing_invalid_target_layer_order():
         assert fwd_context is not None
 
 
-def test_init_kv_cache_with_kv_sharing_target_layer_not_exist():
+def test_init_kv_cache_with_kv_sharing_target_layer_not_exist(default_vllm_config):
     torch.set_default_dtype(torch.float16)
     layer_0 = "model.layers.0.self_attn.attn"
     layer_1 = "model.layers.1.self_attn.attn"
@@ -600,7 +601,7 @@ def test_init_kv_cache_with_kv_sharing_target_layer_not_exist():
         assert fwd_context is not None
 
 
-def test_init_kv_cache_with_kv_sharing_target_same_as_current():
+def test_init_kv_cache_with_kv_sharing_target_same_as_current(default_vllm_config):
     torch.set_default_dtype(torch.float16)
     layer_0 = "model.layers.0.self_attn.attn"
     layer_1 = "model.layers.1.self_attn.attn"
@@ -627,7 +628,7 @@ def test_init_kv_cache_with_kv_sharing_target_same_as_current():
         assert fwd_context is not None
 
 
-def test_init_kv_cache_without_kv_sharing():
+def test_init_kv_cache_without_kv_sharing(default_vllm_config):
     torch.set_default_dtype(torch.float16)
     layer_0 = "model.layers.0.self_attn.attn"
     layer_1 = "model.layers.1.self_attn.attn"
@@ -694,7 +695,7 @@ def test_init_kv_cache_without_kv_sharing():
     assert kv_cache_config.kv_cache_groups[0].layer_names[1] == layer_1
 
 
-def test_init_kv_cache_with_kv_sharing_valid():
+def test_init_kv_cache_with_kv_sharing_valid(default_vllm_config):
     torch.set_default_dtype(torch.float16)
     layer_0 = "model.layers.0.self_attn.attn"
     layer_1 = "model.layers.1.self_attn.attn"
@@ -1047,7 +1048,7 @@ def test_input_batch_with_kernel_block_sizes():
             assert block_table.block_size == kernel_size
 
 
-def test_hybrid_cache_integration(model_runner, dist_init):
+def test_hybrid_cache_integration(default_vllm_config, dist_init):
     """Test hybrid cache architecture integration with GPUModelRunner."""
     # Create a new model runner with hybrid cache configuration
     vllm_config = get_vllm_config()

tests/v1/worker/test_utils.py

@@ -6,14 +6,14 @@ import torch
 from vllm.v1.worker.utils import bind_kv_cache
 
 
-def test_bind_kv_cache():
+def test_bind_kv_cache(default_vllm_config):
     from vllm.attention.layer import Attention
 
     ctx = {
-        "layers.0.self_attn": Attention(32, 128, 0.1),
-        "layers.1.self_attn": Attention(32, 128, 0.1),
-        "layers.2.self_attn": Attention(32, 128, 0.1),
-        "layers.3.self_attn": Attention(32, 128, 0.1),
+        "layers.0.self_attn": Attention(32, 128, 0.1, prefix="layers.0.self_attn"),
+        "layers.1.self_attn": Attention(32, 128, 0.1, prefix="layers.1.self_attn"),
+        "layers.2.self_attn": Attention(32, 128, 0.1, prefix="layers.2.self_attn"),
+        "layers.3.self_attn": Attention(32, 128, 0.1, prefix="layers.3.self_attn"),
     }
     kv_cache = {
         "layers.0.self_attn": torch.zeros((1,)),
@@ -34,13 +34,13 @@ def test_bind_kv_cache():
     assert runner_kv_caches[3] is kv_cache["layers.3.self_attn"]
 
 
-def test_bind_kv_cache_non_attention():
+def test_bind_kv_cache_non_attention(default_vllm_config):
     from vllm.attention.layer import Attention
 
     # example from Jamba PP=2
     ctx = {
-        "model.layers.20.attn": Attention(32, 128, 0.1),
-        "model.layers.28.attn": Attention(32, 128, 0.1),
+        "model.layers.20.attn": Attention(32, 128, 0.1, prefix="model.layers.20.attn"),
+        "model.layers.28.attn": Attention(32, 128, 0.1, prefix="model.layers.28.attn"),
     }
     kv_cache = {
         "model.layers.20.attn": torch.zeros((1,)),

vllm/attention/utils/fa_utils.py

@@ -59,10 +59,13 @@ def get_flash_attn_version(requires_alibi: bool = False) -> int | None:
         )
 
         # 2. override if passed by environment or config
-        from vllm.config import get_current_vllm_config
+        from vllm.config import get_current_vllm_config_or_none
 
-        vllm_config = get_current_vllm_config()
-        if vllm_config.attention_config.flash_attn_version is not None:
+        vllm_config = get_current_vllm_config_or_none()
+        if (
+            vllm_config is not None
+            and vllm_config.attention_config.flash_attn_version is not None
+        ):
             fa_version = vllm_config.attention_config.flash_attn_version
 
         # 3. fallback for unsupported combinations

vllm/config/__init__.py

@@ -42,6 +42,7 @@ from vllm.config.vllm import (
     VllmConfig,
     get_cached_compilation_config,
     get_current_vllm_config,
+    get_current_vllm_config_or_none,
     get_layers_from_vllm_config,
     set_current_vllm_config,
 )
@@ -105,6 +106,7 @@ __all__ = [
     "VllmConfig",
     "get_cached_compilation_config",
     "get_current_vllm_config",
+    "get_current_vllm_config_or_none",
     "set_current_vllm_config",
     "get_layers_from_vllm_config",
 ]

vllm/config/vllm.py

@@ -1441,13 +1441,18 @@ def get_cached_compilation_config():
 
 def get_current_vllm_config() -> VllmConfig:
     if _current_vllm_config is None:
-        # in ci, usually when we test custom ops/modules directly,
-        # we don't set the vllm config. In that case, we set a default
-        # config.
-        # Use stack level 2 so the log contains the line of the caller,
-        # so it's easier to track down the source of the warning.
-        logger.warning("Current vLLM config is not set.", stacklevel=2)
-        return VllmConfig()
+        raise AssertionError(
+            "Current vLLM config is not set. This typically means "
+            "get_current_vllm_config() was called outside of a "
+            "set_current_vllm_config() context, or a CustomOp was instantiated "
+            "at module import time or model forward time when config is not set. "
+            "For tests that directly test custom ops/modules, use the "
+            "'default_vllm_config' pytest fixture from tests/conftest.py."
+        )
+    return _current_vllm_config
+
+
+def get_current_vllm_config_or_none() -> VllmConfig | None:
     return _current_vllm_config