test(models): real-artifact sanity for MRI DL 2D (skips when absent)

tests/models/test_mri_dl_2d_real.py

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+"""Real-artifact sanity. Skipped unless the checkpoint is present.
+
+When the user drops their trained best_model.pt at the canonical path, this
+test runs automatically — catches class-order or input-shape drift.
+"""
+from __future__ import annotations
+
+from pathlib import Path
+
+import numpy as np
+import pytest
+from PIL import Image
+
+from src.models import mri_dl_2d
+
+
+REAL_CKPT = Path("data/processed/mri_dl_2d/best_model.pt")
+
+
+@pytest.mark.skipif(not REAL_CKPT.exists(), reason="real MRI checkpoint not present")
+def test_real_checkpoint_loads_and_predicts(tmp_path):
+    model = mri_dl_2d.load(REAL_CKPT)
+    arr = (np.random.RandomState(0).rand(170, 170, 3) * 255).astype(np.uint8)
+    img = tmp_path / "scan.png"
+    Image.fromarray(arr).save(str(img))
+    result = mri_dl_2d.predict_image(model, img)
+
+    assert result["label_text"] in mri_dl_2d.CLASS_TO_IDX
+    s = sum(p["probability"] for p in result["probabilities"])
+    assert abs(s - 1.0) < 1e-5