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| 1 | +"""Integration test: ``HF.as_null_adapter`` determinism + restoration. |
| 2 | + |
| 3 | +Two contracts the calibration matrix depends on: |
| 4 | + |
| 5 | +1. **Same seed → same null weights.** ``as_null_adapter(seed=0)`` called |
| 6 | + twice in a row must produce bit-identical lora_A / lora_B tensors |
| 7 | + inside the context. If a future PEFT release randomized something |
| 8 | + we missed (e.g. dropout sampling), the cached null stats would be |
| 9 | + silently inconsistent across runs. |
| 10 | +2. **Original adapter restored on exit.** After the context manager |
| 11 | + returns, every ``lora_A`` / ``lora_B`` parameter must equal its |
| 12 | + pre-context value. Otherwise the next probe runs against a |
| 13 | + randomly-poisoned ft view. |
| 14 | + |
| 15 | +Marked ``slow+online`` to share the tiny-model fixture. |
| 16 | +""" |
| 17 | + |
| 18 | +from __future__ import annotations |
| 19 | + |
| 20 | +from pathlib import Path |
| 21 | + |
| 22 | +import numpy as np |
| 23 | +import pytest |
| 24 | + |
| 25 | +from dlm_sway.backends.hf import HuggingFaceDifferentialBackend |
| 26 | +from dlm_sway.core.model import ModelSpec |
| 27 | + |
| 28 | +pytestmark = [pytest.mark.slow, pytest.mark.online] |
| 29 | + |
| 30 | + |
| 31 | +def _build_random_lora_adapter(base_dir: Path, out_dir: Path) -> None: |
| 32 | + """Same shape as the toggle-test adapter.""" |
| 33 | + import torch |
| 34 | + from peft import LoraConfig, get_peft_model |
| 35 | + from transformers import AutoModelForCausalLM, AutoTokenizer |
| 36 | + |
| 37 | + torch.manual_seed(0) |
| 38 | + tokenizer = AutoTokenizer.from_pretrained(str(base_dir)) |
| 39 | + if tokenizer.pad_token_id is None: |
| 40 | + tokenizer.pad_token = tokenizer.eos_token |
| 41 | + base = AutoModelForCausalLM.from_pretrained(str(base_dir), torch_dtype=torch.float32) |
| 42 | + cfg = LoraConfig( |
| 43 | + r=8, |
| 44 | + lora_alpha=16, |
| 45 | + target_modules=["q_proj", "v_proj"], |
| 46 | + lora_dropout=0.0, |
| 47 | + bias="none", |
| 48 | + task_type="CAUSAL_LM", |
| 49 | + ) |
| 50 | + peft_model = get_peft_model(base, cfg) |
| 51 | + with torch.no_grad(): |
| 52 | + for name, param in peft_model.named_parameters(): |
| 53 | + if "lora_B" in name: |
| 54 | + param.copy_(torch.randn_like(param) * 0.05) |
| 55 | + peft_model.save_pretrained(str(out_dir)) |
| 56 | + tokenizer.save_pretrained(str(out_dir)) |
| 57 | + |
| 58 | + |
| 59 | +@pytest.fixture(scope="module") |
| 60 | +def random_adapter(tiny_model_dir: Path, tmp_path_factory: pytest.TempPathFactory) -> Path: |
| 61 | + adapter_dir = tmp_path_factory.mktemp("null-random-adapter") |
| 62 | + _build_random_lora_adapter(tiny_model_dir, adapter_dir) |
| 63 | + return adapter_dir |
| 64 | + |
| 65 | + |
| 66 | +@pytest.fixture(scope="module") |
| 67 | +def hf_backend(tiny_model_dir: Path, random_adapter: Path) -> HuggingFaceDifferentialBackend: |
| 68 | + backend = HuggingFaceDifferentialBackend( |
| 69 | + base_spec=ModelSpec(base=str(tiny_model_dir), kind="hf", dtype="fp32", device="cpu"), |
| 70 | + adapter_path=random_adapter, |
| 71 | + ) |
| 72 | + yield backend |
| 73 | + backend.close() |
| 74 | + |
| 75 | + |
| 76 | +def _snapshot_lora_params(backend: HuggingFaceDifferentialBackend) -> dict[str, np.ndarray]: |
| 77 | + """Capture every lora_A / lora_B parameter as a numpy copy.""" |
| 78 | + out: dict[str, np.ndarray] = {} |
| 79 | + for pname, param in backend._peft_model.named_parameters(): # type: ignore[attr-defined] |
| 80 | + if any(key in pname for key in ("lora_A", "lora_B")): |
| 81 | + out[pname] = param.detach().cpu().numpy().copy() |
| 82 | + return out |
| 83 | + |
| 84 | + |
| 85 | +def test_same_seed_produces_identical_null_weights( |
| 86 | + hf_backend: HuggingFaceDifferentialBackend, |
| 87 | +) -> None: |
| 88 | + with hf_backend.as_null_adapter(seed=0): |
| 89 | + first = _snapshot_lora_params(hf_backend) |
| 90 | + with hf_backend.as_null_adapter(seed=0): |
| 91 | + second = _snapshot_lora_params(hf_backend) |
| 92 | + assert set(first) == set(second) |
| 93 | + for key in first: |
| 94 | + np.testing.assert_array_equal( |
| 95 | + first[key], |
| 96 | + second[key], |
| 97 | + err_msg=f"as_null_adapter(seed=0) was not deterministic for {key!r}", |
| 98 | + ) |
| 99 | + |
| 100 | + |
| 101 | +def test_different_seeds_produce_different_null_weights( |
| 102 | + hf_backend: HuggingFaceDifferentialBackend, |
| 103 | +) -> None: |
| 104 | + with hf_backend.as_null_adapter(seed=0): |
| 105 | + a = _snapshot_lora_params(hf_backend) |
| 106 | + with hf_backend.as_null_adapter(seed=1): |
| 107 | + b = _snapshot_lora_params(hf_backend) |
| 108 | + different = any(not np.array_equal(a[k], b[k]) for k in a) |
| 109 | + assert different, "null adapters at seed=0 and seed=1 produced identical weights" |
| 110 | + |
| 111 | + |
| 112 | +def test_original_adapter_restored_on_exit( |
| 113 | + hf_backend: HuggingFaceDifferentialBackend, |
| 114 | +) -> None: |
| 115 | + before = _snapshot_lora_params(hf_backend) |
| 116 | + with hf_backend.as_null_adapter(seed=42): |
| 117 | + # confirm the inner state is *not* the original |
| 118 | + inner = _snapshot_lora_params(hf_backend) |
| 119 | + assert any(not np.array_equal(before[k], inner[k]) for k in before) |
| 120 | + after = _snapshot_lora_params(hf_backend) |
| 121 | + for key in before: |
| 122 | + np.testing.assert_array_equal( |
| 123 | + before[key], |
| 124 | + after[key], |
| 125 | + err_msg=f"original adapter not restored for {key!r}", |
| 126 | + ) |
| 127 | + |
| 128 | + |
| 129 | +def test_original_adapter_restored_on_exception( |
| 130 | + hf_backend: HuggingFaceDifferentialBackend, |
| 131 | +) -> None: |
| 132 | + before = _snapshot_lora_params(hf_backend) |
| 133 | + with pytest.raises(RuntimeError, match="boom"): |
| 134 | + with hf_backend.as_null_adapter(seed=99): |
| 135 | + raise RuntimeError("boom") |
| 136 | + after = _snapshot_lora_params(hf_backend) |
| 137 | + for key in before: |
| 138 | + np.testing.assert_array_equal( |
| 139 | + before[key], |
| 140 | + after[key], |
| 141 | + err_msg=f"original adapter not restored after exception for {key!r}", |
| 142 | + ) |
