test: add unit tests for make_detector factory (#48)

tests/test_factory_pytest.py

@@ -0,0 +1,54 @@
+"""Pytest tests for the detector factory (``make_detector``)."""
+
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from lettucedetect.detectors.factory import make_detector
+
+
+class TestMakeDetector:
+    """Tests for the ``make_detector`` factory function."""
+
+    def test_transformer_method_returns_transformer_detector(self):
+        """``method="transformer"`` builds a TransformerDetector with the given kwargs."""
+        mock_detector = MagicMock()
+        with patch(
+            "lettucedetect.detectors.transformer.TransformerDetector",
+            return_value=mock_detector,
+        ) as mock_cls:
+            result = make_detector("transformer", model_path="dummy_path")
+            mock_cls.assert_called_once_with(model_path="dummy_path")
+            assert result is mock_detector
+
+    def test_llm_method_returns_llm_detector(self):
+        """``method="llm"`` builds an LLMDetector with the given kwargs."""
+        mock_detector = MagicMock()
+        with patch(
+            "lettucedetect.detectors.llm.LLMDetector",
+            return_value=mock_detector,
+        ) as mock_cls:
+            result = make_detector("llm", model="gpt-4.1-mini")
+            mock_cls.assert_called_once_with(model="gpt-4.1-mini")
+            assert result is mock_detector
+
+    def test_rag_fact_checker_method_returns_rag_detector(self):
+        """``method="rag_fact_checker"`` builds a RAGFactCheckerDetector."""
+        mock_detector = MagicMock()
+        with patch(
+            "lettucedetect.detectors.rag_fact_checker.RAGFactCheckerDetector",
+            return_value=mock_detector,
+        ) as mock_cls:
+            result = make_detector("rag_fact_checker")
+            mock_cls.assert_called_once_with()
+            assert result is mock_detector
+
+    def test_unknown_method_raises_value_error(self):
+        """An unsupported method raises ``ValueError`` listing the valid options."""
+        with pytest.raises(ValueError) as exc_info:
+            make_detector("bogus")
+        message = str(exc_info.value)
+        assert "bogus" in message
+        assert "transformer" in message
+        assert "llm" in message
+        assert "rag_fact_checker" in message