remove llamastack neural reranker and add unit tests

Signed-off-by: Anxhela Coba <acoba@redhat.com>

Author: Anxhela21

src/models/config.py

@@ -1827,8 +1827,6 @@ class RerankerConfiguration(ConfigurationBase):
         description="Cross-encoder model name for reranking RAG chunks. "
         "Defaults to 'cross-encoder/ms-marco-MiniLM-L6-v2' from sentence-transformers.",
     )
-    model_id: str = "meta-llama/llama-cross-encoder-base"
-    provider_id: str = "meta-reference"
     top_k_multiplier: float = 2.0  # fetch 2x, rerank, keep top_k
     byok_boost: float = 1.2
     okp_boost: float = 1.0
@@ -1843,8 +1841,6 @@ def mark_as_explicitly_configured(self) -> Self:
         # This allows auto-enabling when user hasn't touched reranker settings
         # Check if any field differs from default values
         default_model = "cross-encoder/ms-marco-MiniLM-L6-v2"
-        default_model_id = "meta-llama/llama-cross-encoder-base"
-        default_provider_id = "meta-reference"
         default_top_k_multiplier = 2.0
         default_byok_boost = 1.2
         default_okp_boost = 1.0
@@ -1853,17 +1849,13 @@ def mark_as_explicitly_configured(self) -> Self:
         current_values = [
             self.enabled,
             self.model,
-            self.model_id,
-            self.provider_id,
             self.top_k_multiplier,
             self.byok_boost,
             self.okp_boost,
         ]
         default_values = [
             True,
             default_model,
-            default_model_id,
-            default_provider_id,
             default_top_k_multiplier,
             default_byok_boost,
             default_okp_boost,

tests/unit/models/config/test_reranker_configuration.py

@@ -0,0 +1,75 @@
+"""Unit tests for RerankerConfiguration model."""
+
+import pytest
+from pydantic import ValidationError
+
+from models.config import RerankerConfiguration
+
+
+class TestRerankerConfiguration:
+    """Tests for RerankerConfiguration model."""
+
+    def test_default_values(self) -> None:
+        """Test that RerankerConfiguration has correct default values."""
+        config = RerankerConfiguration()
+        assert config.enabled is True
+        assert config.model == "cross-encoder/ms-marco-MiniLM-L6-v2"
+        assert config.top_k_multiplier == 2.0
+        assert config.byok_boost == 1.2
+        assert config.okp_boost == 1.0
+
+    def test_custom_model(self) -> None:
+        """Test configuration with custom cross-encoder model."""
+        config = RerankerConfiguration(
+            model="cross-encoder/ms-marco-TinyBERT-L2-v2"
+        )
+        assert config.model == "cross-encoder/ms-marco-TinyBERT-L2-v2"
+        assert config.enabled is True
+
+    def test_disabled_reranker(self) -> None:
+        """Test configuration with reranker disabled."""
+        config = RerankerConfiguration(enabled=False)
+        assert config.enabled is False
+        assert config.model == "cross-encoder/ms-marco-MiniLM-L6-v2"
+
+    def test_custom_boost_factors(self) -> None:
+        """Test configuration with custom boost factors."""
+        config = RerankerConfiguration(
+            byok_boost=1.5,
+            okp_boost=0.8
+        )
+        assert config.byok_boost == 1.5
+        assert config.okp_boost == 0.8
+
+    def test_custom_top_k_multiplier(self) -> None:
+        """Test configuration with custom top_k_multiplier."""
+        config = RerankerConfiguration(top_k_multiplier=3.0)
+        assert config.top_k_multiplier == 3.0
+
+    def test_all_custom_values(self) -> None:
+        """Test configuration with all custom values."""
+        config = RerankerConfiguration(
+            enabled=False,
+            model="custom-cross-encoder",
+            top_k_multiplier=1.5,
+            byok_boost=2.0,
+            okp_boost=0.5
+        )
+        assert config.enabled is False
+        assert config.model == "custom-cross-encoder"
+        assert config.top_k_multiplier == 1.5
+        assert config.byok_boost == 2.0
+        assert config.okp_boost == 0.5
+
+    def test_explicit_configuration_detection(self) -> None:
+        """Test that explicitly configured values are detected."""
+        # Non-default values should mark as explicitly configured
+        config = RerankerConfiguration(enabled=False)
+        assert hasattr(config, "_explicitly_configured")
+        # Note: The actual _explicitly_configured logic is private
+        # and tested through integration tests
+
+    def test_invalid_field_rejected(self) -> None:
+        """Test that invalid fields are rejected due to extra='forbid'."""
+        with pytest.raises(ValidationError):
+            RerankerConfiguration(invalid_field="value")