fix: validate scorer instance names in config (#407)

* fix: validate scorer instance names in config

* fix: run scorer config tests in CI

* fix: drop redundant UV_PYTHON env and quote unittest pattern

* fix: report precise scorer name validation errors

src/heretic/config.py

@@ -9,6 +9,7 @@ from pydantic import (
     Field,
     NonNegativeInt,
     PositiveInt,
+    field_validator,
 )
 from pydantic_settings import (
     BaseSettings,
@@ -123,6 +124,23 @@ class ScorerConfig(BaseModel):
         ),
     )
 
+    @field_validator("instance_name")
+    @classmethod
+    def validate_instance_name(cls, value: str | None) -> str | None:
+        if value is None:
+            return value
+
+        if not value.strip():
+            raise ValueError("cannot be empty or whitespace")
+
+        if "." in value:
+            raise ValueError("'.' is not allowed")
+
+        if any(char.isspace() for char in value):
+            raise ValueError("whitespace is not allowed")
+
+        return value
+
 
 class BenchmarkSpecification(BaseModel):
     task: str = Field(

src/heretic/evaluator.py

@@ -67,18 +67,6 @@ class Evaluator:
             # Instantiate scorers.
             instance_name = config.instance_name or None
 
-            if instance_name is not None:
-                if not instance_name.strip():
-                    raise ValueError(
-                        f"Invalid instance_name {instance_name} for scorer {scorer_cls.__name__}: "
-                        "cannot be empty or whitespace"
-                    )
-                if "." in instance_name or " " in instance_name:
-                    raise ValueError(
-                        f"Invalid instance_name {instance_name} for scorer {scorer_cls.__name__}: "
-                        "'.' and whitespace are not allowed"
-                    )
-
             raw_settings = self._get_scorer_settings_raw(
                 scorer_cls=scorer_cls, instance_name=instance_name
             )