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vllm-omni/tests/diffusion/models/bagel/test_bagel_lora.py
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# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Unit tests for BAGEL LoRA support across Stage 0 (Thinker) and Stage 1 (DiT)."""
from __future__ import annotations
import json
from pathlib import Path
import pytest
import torch
from safetensors.torch import save_file
from tests.diffusion.lora.helpers import (
DummyBaseLayerWithLoRA,
FakeLinearBase,
fake_replace_submodule,
)
from vllm_omni.diffusion.lora.manager import DiffusionLoRAManager
from vllm_omni.lora.request import LoRARequest
pytestmark = [pytest.mark.core_model, pytest.mark.cpu]
_FakeLinearBase = FakeLinearBase
# ---------------------------------------------------------------------------
# Stage 0 (Thinker / AR) -- packed_modules_mapping on the AR model class
# ---------------------------------------------------------------------------
class TestStage0ThinkerLoRA:
"""Validate that OmniBagelForConditionalGeneration declares correct LoRA metadata."""
def test_omni_bagel_supports_lora(self):
from vllm_omni.model_executor.models.bagel.bagel import (
OmniBagelForConditionalGeneration,
)
assert getattr(OmniBagelForConditionalGeneration, "supports_lora", False) is True
def test_omni_bagel_packed_modules_mapping_complete(self):
from vllm_omni.model_executor.models.bagel.bagel import (
OmniBagelForConditionalGeneration,
)
mapping = OmniBagelForConditionalGeneration.packed_modules_mapping
# Standard Qwen2 projections
assert mapping["qkv_proj"] == ["q_proj", "k_proj", "v_proj"]
assert mapping["gate_up_proj"] == ["gate_proj", "up_proj"]
# MoE generation-mode projections
assert mapping["qkv_proj_moe_gen"] == [
"q_proj_moe_gen",
"k_proj_moe_gen",
"v_proj_moe_gen",
]
assert mapping["mlp_moe_gen.gate_up_proj"] == [
"mlp_moe_gen.gate_proj",
"mlp_moe_gen.up_proj",
]
# ---------------------------------------------------------------------------
# Stage 1 (DiT / Diffusion) -- DiffusionLoRAManager with bagel component
# ---------------------------------------------------------------------------
class TestStage1DiTLoRA:
"""Validate DiffusionLoRAManager discovers BAGEL's packed modules."""
def test_diffusion_lora_manager_discovers_bagel_packed_modules(self):
"""Manager should derive packed→sublayer mapping from stacked_params_mapping."""
pipeline = torch.nn.Module()
pipeline.bagel = torch.nn.Module()
# Simulate a submodule that exposes stacked_params_mapping
# (as Bagel does after load_weights())
language_model = torch.nn.Module()
language_model.stacked_params_mapping = [
(".qkv_proj_moe_gen", ".q_proj_moe_gen", "q"),
(".qkv_proj_moe_gen", ".k_proj_moe_gen", "k"),
(".qkv_proj_moe_gen", ".v_proj_moe_gen", "v"),
(".qkv_proj", ".q_proj", "q"),
(".qkv_proj", ".k_proj", "k"),
(".qkv_proj", ".v_proj", "v"),
(".gate_up_proj", ".gate_proj", 0),
(".gate_up_proj", ".up_proj", 1),
]
pipeline.bagel.language_model = language_model
manager = DiffusionLoRAManager(
pipeline=pipeline,
device=torch.device("cpu"),
dtype=torch.bfloat16,
max_cached_adapters=1,
)
mapping = manager._packed_modules_mapping
assert mapping["qkv_proj"] == ["q_proj", "k_proj", "v_proj"]
assert mapping["qkv_proj_moe_gen"] == [
"q_proj_moe_gen",
"k_proj_moe_gen",
"v_proj_moe_gen",
]
assert mapping["gate_up_proj"] == ["gate_proj", "up_proj"]
def test_diffusion_lora_manager_replaces_bagel_packed_layer_via_sublayer_target(self, monkeypatch):
"""Targeting sublayer 'q_proj' should replace the fused 'qkv_proj' under bagel."""
import vllm_omni.diffusion.lora.manager as manager_mod
monkeypatch.setattr(manager_mod, "BaseLayerWithLoRA", DummyBaseLayerWithLoRA)
def _fake_from_layer_diffusion(*, layer, **_kwargs):
return DummyBaseLayerWithLoRA(layer)
replace_calls: list[str] = []
monkeypatch.setattr(manager_mod, "from_layer_diffusion", _fake_from_layer_diffusion)
monkeypatch.setattr(
manager_mod,
"replace_submodule",
lambda root, name, sub: fake_replace_submodule(root, name, sub, replace_calls),
)
# Build pipeline with bagel component
pipeline = torch.nn.Module()
pipeline.bagel = torch.nn.Module()
lm = torch.nn.Module()
lm.stacked_params_mapping = [
(".qkv_proj", ".q_proj", "q"),
(".qkv_proj", ".k_proj", "k"),
(".qkv_proj", ".v_proj", "v"),
]
lm.attn = torch.nn.Module()
lm.attn.qkv_proj = _FakeLinearBase()
pipeline.bagel.language_model = lm
manager = DiffusionLoRAManager(
pipeline=pipeline,
device=torch.device("cpu"),
dtype=torch.bfloat16,
max_cached_adapters=1,
)
# Treat qkv_proj as 3-slice packed layer
monkeypatch.setattr(manager, "_get_packed_modules_list", lambda _module: ["q", "k", "v"])
# Target sublayer "q_proj" -- manager should replace the packed "qkv_proj"
peft_helper = type("_PH", (), {"r": 1, "target_modules": ["q_proj"]})()
manager._replace_layers_with_lora(peft_helper)
assert "language_model.attn.qkv_proj" in replace_calls
assert "bagel.language_model.attn.qkv_proj" in manager._lora_modules
# Verify the module was actually replaced in the tree (not just recorded)
assert isinstance(pipeline.bagel.language_model.attn.qkv_proj, DummyBaseLayerWithLoRA)
# ---------------------------------------------------------------------------
# Round-trip: synthetic checkpoint → set_active_adapter → verify weights
# ---------------------------------------------------------------------------
def _write_synthetic_lora(
adapter_dir: Path,
module_name: str,
rank: int,
in_dim: int,
out_dim: int,
) -> str:
"""Write a minimal LoRA adapter (safetensors + config) to *adapter_dir*."""
adapter_dir.mkdir(parents=True, exist_ok=True)
lora_a = torch.ones((rank, in_dim), dtype=torch.float32)
lora_b = torch.ones((out_dim, rank), dtype=torch.float32) * 2.0
save_file(
{
f"base_model.model.{module_name}.lora_A.weight": lora_a,
f"base_model.model.{module_name}.lora_B.weight": lora_b,
},
str(adapter_dir / "adapter_model.safetensors"),
)
(adapter_dir / "adapter_config.json").write_text(
json.dumps({"r": rank, "lora_alpha": rank, "target_modules": [module_name]}),
encoding="utf-8",
)
return str(adapter_dir)
class TestBagelLoRARoundTrip:
"""End-to-end: synthetic checkpoint → load → activate → verify weights in fused layer."""
def test_set_active_adapter_loads_and_activates_bagel_lora(self, tmp_path, monkeypatch):
"""Full round-trip through set_active_adapter for a bagel component module."""
import vllm_omni.diffusion.lora.manager as manager_mod
monkeypatch.setattr(manager_mod, "BaseLayerWithLoRA", DummyBaseLayerWithLoRA)
# Build pipeline with bagel.language_model.foo (simple non-packed layer)
pipeline = torch.nn.Module()
pipeline.bagel = torch.nn.Module()
lm = torch.nn.Module()
lm.foo = _FakeLinearBase()
pipeline.bagel.language_model = lm
def _fake_from_layer(*, layer, **_kwargs):
if isinstance(layer, FakeLinearBase):
return DummyBaseLayerWithLoRA(layer)
return layer
monkeypatch.setattr(manager_mod, "from_layer_diffusion", _fake_from_layer)
monkeypatch.setattr(
manager_mod,
"replace_submodule",
lambda root, name, sub: fake_replace_submodule(root, name, sub),
)
manager = DiffusionLoRAManager(
pipeline=pipeline,
device=torch.device("cpu"),
dtype=torch.bfloat16,
max_cached_adapters=1,
)
# Write synthetic adapter targeting bagel.language_model.foo
module_name = "bagel.language_model.foo"
rank = 2
in_dim = 4
out_dim = 4
lora_dir = _write_synthetic_lora(tmp_path / "lora", module_name, rank, in_dim, out_dim)
lora_request = LoRARequest(
lora_name="test_bagel",
lora_int_id=42,
lora_path=lora_dir,
)
# Full round-trip: load from disk → replace layer → activate weights
manager.set_active_adapter(lora_request, lora_scale=0.5)
# Verify the layer was replaced and weights were set
replaced_layer = pipeline.bagel.language_model.foo
assert isinstance(replaced_layer, DummyBaseLayerWithLoRA), "Layer should be wrapped with LoRA"
assert len(replaced_layer.set_calls) == 1, "set_lora should have been called once"
lora_a, lora_b = replaced_layer.set_calls[0]
# A weights should be ones (as written)
assert torch.all(lora_a == 1.0), f"lora_a should be all ones, got {lora_a}"
# B weights should be 2.0 * scale(0.5) = 1.0
assert torch.allclose(lora_b, torch.ones_like(lora_b)), f"lora_b should be 2.0 * 0.5 = 1.0, got {lora_b}"