Add configurable library reference roots

serato_doctor/config.py

@@ -0,0 +1,25 @@
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Iterable, Tuple
+
+
+@dataclass(frozen=True)
+class ScanConfig:
+    """Read-only paths used for one library scan."""
+
+    serato: Path
+    music: Path
+    out: Path
+    report: Path
+    reference_roots: Tuple[Path, ...] = ()
+
+    @classmethod
+    def build(
+        cls,
+        serato: Path,
+        music: Path,
+        out: Path,
+        report: Path,
+        reference_roots: Iterable[Path] = (),
+    ) -> "ScanConfig":
+        return cls(serato, music, out, report, tuple(reference_roots))