test: 单元测试与端到端冒烟

88 个测试覆盖配置继承、注册表、GPU 守卫、YOLO 格式解析、数据集、模型形状、
标签模式、聚类原语与 SimCLR 损失，以及 train.py / eval.py / 聚类脚本的入口接线。

含两条回归测试：
- PCA 白化放大噪声方向导致簇塌陷（默认 whiten=False 的依据）
- classes 写成 data.yaml 路径时 num_classes 必须是类别数而非路径字符串长度

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_config.py

@@ -0,0 +1,48 @@
+import pytest
+
+pytest.importorskip("yaml")
+
+from utils.config import Config, apply_overrides, deep_merge, load_config, parse_override  # noqa: E402
+
+
+def test_deep_merge_is_recursive():
+    merged = deep_merge({"a": {"b": 1, "c": 2}}, {"a": {"c": 3}, "d": 4})
+    assert merged == {"a": {"b": 1, "c": 3}, "d": 4}
+
+
+def test_parse_override_literals():
+    assert parse_override("train.lr=1e-3") == ("train.lr", 1e-3)
+    assert parse_override("train.amp=False") == ("train.amp", False)
+    assert parse_override("model.backbone.name=tiny_conv") == ("model.backbone.name", "tiny_conv")
+
+
+def test_apply_overrides_creates_missing_nodes():
+    cfg = apply_overrides({}, ["a.b.c=1"])
+    assert cfg == {"a": {"b": {"c": 1}}}
+
+
+def test_load_config_with_base(tmp_path):
+    (tmp_path / "base.yaml").write_text("train:\n  lr: 0.1\n  epochs: 10\n", encoding="utf-8")
+    (tmp_path / "child.yaml").write_text(
+        "_base_: ./base.yaml\ntrain:\n  lr: 0.01\nwork_dir: runs/x\n", encoding="utf-8"
+    )
+
+    cfg = load_config(tmp_path / "child.yaml", ["train.epochs=2"])
+    assert isinstance(cfg, Config)
+    assert cfg.train.lr == 0.01
+    assert cfg.train.epochs == 2
+    assert cfg.get_path("work_dir") == "runs/x"
+
+
+def test_load_config_detects_cycle(tmp_path):
+    (tmp_path / "a.yaml").write_text("_base_: ./b.yaml\n", encoding="utf-8")
+    (tmp_path / "b.yaml").write_text("_base_: ./a.yaml\n", encoding="utf-8")
+    with pytest.raises(ValueError, match="循环引用"):
+        load_config(tmp_path / "a.yaml")
+
+
+def test_project_configs_are_loadable():
+    cfg = load_config("configs/train/baseline.yaml")
+    assert cfg["model"]["name"] == "defect_net"
+    assert cfg["data"]["train"]["dataset"]["name"] == "film_defect"
+    assert len(cfg["classes"]) > 0