Fix test imports: move helpers to importable module

conftest.py is auto-loaded by pytest and can't be imported as a
regular module. Move get_device/skip_if_no_metal to helpers.py
and remove __init__.py so pytest adds tests/ to sys.path.

Co-developed-by: Claude Code v2.1.58 (claude-opus-4-6)

Author: robtaylor

tests/__init__.py

@@ -1,42 +1,8 @@
-"""Shared test utilities for Metal kernel tests."""
+"""Pytest conftest — fixtures auto-injected by pytest."""
 
 import pytest
-import torch
 
-
-# ── Device detection ──
-
-
-def get_device():
-    """Get the best available compute device."""
-    if hasattr(torch.backends, "mps") and torch.backends.mps.is_available():
-        return torch.device("mps")
-    if torch.cuda.is_available():
-        return torch.device("cuda")
-    return torch.device("cpu")
-
-
-def skip_if_no_metal():
-    """Skip test if MPS device is not available."""
-    if get_device().type != "mps":
-        pytest.skip("Metal kernel requires MPS device")
-
-
-# ── Tolerance helpers ──
-
-DEFAULT_TOLERANCES = {
-    torch.float32: {"atol": 1e-5, "rtol": 1e-5},
-    torch.float16: {"atol": 1e-3, "rtol": 1e-3},
-    torch.bfloat16: {"atol": 1e-2, "rtol": 1.6e-2},
-}
-
-
-def get_tolerances(dtype):
-    """Get atol/rtol for a given dtype."""
-    return DEFAULT_TOLERANCES.get(dtype, {"atol": 0.1, "rtol": 0.1})
-
-
-# ── Fixtures ──
+from helpers import get_device
 
 
 @pytest.fixture

tests/conftest.py

@@ -0,0 +1,31 @@
+"""Shared test helpers for Metal kernel tests."""
+
+import pytest
+import torch
+
+
+def get_device():
+    """Get the best available compute device."""
+    if hasattr(torch.backends, "mps") and torch.backends.mps.is_available():
+        return torch.device("mps")
+    if torch.cuda.is_available():
+        return torch.device("cuda")
+    return torch.device("cpu")
+
+
+def skip_if_no_metal():
+    """Skip test if MPS device is not available."""
+    if get_device().type != "mps":
+        pytest.skip("Metal kernel requires MPS device")
+
+
+DEFAULT_TOLERANCES = {
+    torch.float32: {"atol": 1e-5, "rtol": 1e-5},
+    torch.float16: {"atol": 1e-3, "rtol": 1e-3},
+    torch.bfloat16: {"atol": 1e-2, "rtol": 1.6e-2},
+}
+
+
+def get_tolerances(dtype):
+    """Get atol/rtol for a given dtype."""
+    return DEFAULT_TOLERANCES.get(dtype, {"atol": 0.1, "rtol": 0.1})

tests/helpers.py

@@ -3,7 +3,7 @@
 import pytest
 import torch
 
-from conftest import get_device, skip_if_no_metal
+from helpers import get_device, skip_if_no_metal
 
 
 # ── Pure PyTorch reference implementations ──