Add judge_language config plumbing (settings + scenario + ScoreRequest)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/test_judge_language_config.py

@@ -0,0 +1,72 @@
+"""Tests for judge_language plumbing across settings, scenario schema, and loader."""
+
+from pathlib import Path
+
+import pytest
+
+from rag_eval.settings import EvaluationSettings
+from rag_eval.config.loader import load_scenario
+
+
+def test_settings_default_judge_language_is_en():
+    """ragas_judge_language defaults to 'en' when the env var is absent."""
+    settings = EvaluationSettings(_env_file=None)
+    assert settings.ragas_judge_language == "en"
+
+
+def _write_scenario(tmp_path: Path, extra: str) -> Path:
+    """Write a minimal valid offline scenario YAML plus the given extra line(s)."""
+    dataset = tmp_path / "data.csv"
+    dataset.write_text("sample_id,question,answer,contexts,ground_truth\n", encoding="utf-8")
+    text = (
+        "scenario_name: t\n"
+        "mode: offline\n"
+        f"dataset: {dataset.name}\n"
+        "judge_model: gpt-5\n"
+        "embedding_model: text-embedding-3-small\n"
+        "metrics: [faithfulness]\n"
+        "output_dir: out\n"
+        f"{extra}"
+    )
+    path = tmp_path / "s.yaml"
+    path.write_text(text, encoding="utf-8")
+    return path
+
+
+def test_scenario_loads_judge_language_zh(tmp_path):
+    """A scenario may declare judge_language: zh and it lands on the dataclass."""
+    path = _write_scenario(tmp_path, "judge_language: zh\n")
+    scenario = load_scenario(path)
+    assert scenario.judge_language == "zh"
+
+
+def test_scenario_defaults_judge_language_none(tmp_path):
+    """Omitting judge_language leaves it None so the factory can apply the settings default."""
+    path = _write_scenario(tmp_path, "")
+    scenario = load_scenario(path)
+    assert scenario.judge_language is None
+
+
+def test_scenario_rejects_invalid_judge_language(tmp_path):
+    """An unsupported judge_language value is rejected at schema validation."""
+    path = _write_scenario(tmp_path, "judge_language: fr\n")
+    with pytest.raises(Exception):
+        load_scenario(path)
+
+
+def test_score_request_judge_language_defaults_none():
+    """ScoreRequest exposes an optional judge_language defaulting to None."""
+    from webapp.models import ScoreRequest
+
+    req = ScoreRequest(question="q", answer="a")
+    assert req.judge_language is None
+    req_zh = ScoreRequest(question="q", answer="a", judge_language="zh")
+    assert req_zh.judge_language == "zh"
+
+
+def test_session_score_request_inherits_judge_language():
+    """SessionScoreRequest inherits the judge_language field from ScoreRequest."""
+    from webapp.models import SessionScoreRequest
+
+    req = SessionScoreRequest(session_id="s1", question="q", answer="a", judge_language="zh")
+    assert req.judge_language == "zh"