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| 1 | +"""Unit tests for the pure helpers inside ``backends/hf.py``. |
| 2 | + |
| 3 | +The helpers (``_resolve_dtype``, ``_detect_device``) gate the HF |
| 4 | +backend's dtype/device choices. They're exercised end-to-end by the |
| 5 | +integration suite, but doing direct unit coverage on them keeps the |
| 6 | +slow lane focused on the actual backend behavior — and makes the |
| 7 | +fast lane catch dtype/device regressions in seconds. |
| 8 | +""" |
| 9 | + |
| 10 | +from __future__ import annotations |
| 11 | + |
| 12 | +import importlib.util |
| 13 | + |
| 14 | +import pytest |
| 15 | + |
| 16 | +# These tests need torch to construct the dtype objects we're asserting |
| 17 | +# on; skip cleanly when the [hf] extra isn't installed. |
| 18 | +if importlib.util.find_spec("torch") is None: |
| 19 | + pytest.skip( |
| 20 | + "torch not installed — install the [hf] extra to run HF helper tests", |
| 21 | + allow_module_level=True, |
| 22 | + ) |
| 23 | + |
| 24 | +from dlm_sway.backends.hf import _detect_device, _resolve_dtype |
| 25 | + |
| 26 | + |
| 27 | +class TestResolveDtype: |
| 28 | + def test_explicit_fp16(self) -> None: |
| 29 | + import torch |
| 30 | + |
| 31 | + assert _resolve_dtype("fp16", "cpu") is torch.float16 |
| 32 | + |
| 33 | + def test_explicit_bf16(self) -> None: |
| 34 | + import torch |
| 35 | + |
| 36 | + assert _resolve_dtype("bf16", "cpu") is torch.bfloat16 |
| 37 | + |
| 38 | + def test_explicit_fp32(self) -> None: |
| 39 | + import torch |
| 40 | + |
| 41 | + assert _resolve_dtype("fp32", "cpu") is torch.float32 |
| 42 | + |
| 43 | + def test_auto_on_cpu_picks_fp32_for_numerical_stability(self) -> None: |
| 44 | + import torch |
| 45 | + |
| 46 | + assert _resolve_dtype("auto", "cpu") is torch.float32 |
| 47 | + |
| 48 | + def test_auto_on_mps_picks_fp16(self) -> None: |
| 49 | + import torch |
| 50 | + |
| 51 | + assert _resolve_dtype("auto", "mps") is torch.float16 |
| 52 | + |
| 53 | + |
| 54 | +class TestDetectDevice: |
| 55 | + def test_returns_one_of_supported_devices(self) -> None: |
| 56 | + device = _detect_device() |
| 57 | + assert device in ("cuda", "mps", "cpu") |
