feat: add test framework for classifier with dependency injection

src/semantic-router/pkg/utils/classification/classifier.go

@@ -12,6 +12,48 @@ import (
 	"github.com/vllm-project/semantic-router/semantic-router/pkg/metrics"
 )
 
+type CategoryInference interface {
+	Classify(text string) (candle_binding.ClassResult, error)
+}
+
+type LinearCategoryInference struct{}
+
+func (c *LinearCategoryInference) Classify(text string) (candle_binding.ClassResult, error) {
+	return candle_binding.ClassifyText(text)
+}
+
+type ModernBertCategoryInference struct{}
+
+func (c *ModernBertCategoryInference) Classify(text string) (candle_binding.ClassResult, error) {
+	return candle_binding.ClassifyModernBertText(text)
+}
+
+type JailbreakInference interface {
+	Classify(text string) (candle_binding.ClassResult, error)
+}
+
+type LinearJailbreakInference struct{}
+
+func (c *LinearJailbreakInference) Classify(text string) (candle_binding.ClassResult, error) {
+	return candle_binding.ClassifyJailbreakText(text)
+}
+
+type ModernBertJailbreakInference struct{}
+
+func (c *ModernBertJailbreakInference) Classify(text string) (candle_binding.ClassResult, error) {
+	return candle_binding.ClassifyModernBertJailbreakText(text)
+}
+
+type PIIInference interface {
+	ClassifyTokens(text string, configPath string) (candle_binding.TokenClassificationResult, error)
+}
+
+type ModernBertPIIInference struct{}
+
+func (c *ModernBertPIIInference) ClassifyTokens(text string, configPath string) (candle_binding.TokenClassificationResult, error) {
+	return candle_binding.ClassifyModernBertPIITokens(text, configPath)
+}
+
 // JailbreakDetection represents the result of jailbreak analysis for a piece of content
 type JailbreakDetection struct {
 	Content       string  `json:"content"`
@@ -40,6 +82,11 @@ type PIIAnalysisResult struct {
 
 // Classifier handles text classification, model selection, and jailbreak detection functionality
 type Classifier struct {
+	// Dependencies
+	categoryInference  CategoryInference
+	jailbreakInference JailbreakInference
+	piiInference       PIIInference
+
 	Config           *config.RouterConfig
 	CategoryMapping  *CategoryMapping
 	PIIMapping       *PIIMapping
@@ -54,7 +101,27 @@ type Classifier struct {
 
 // NewClassifier creates a new classifier with model selection and jailbreak detection capabilities
 func NewClassifier(cfg *config.RouterConfig, categoryMapping *CategoryMapping, piiMapping *PIIMapping, jailbreakMapping *JailbreakMapping, modelTTFT map[string]float64) *Classifier {
+	var categoryInference CategoryInference
+	if cfg.Classifier.CategoryModel.UseModernBERT {
+		categoryInference = &ModernBertCategoryInference{}
+	} else {
+		categoryInference = &LinearCategoryInference{}
+	}
+
+	var jailbreakInference JailbreakInference
+	if cfg.PromptGuard.UseModernBERT {
+		jailbreakInference = &ModernBertJailbreakInference{}
+	} else {
+		jailbreakInference = &LinearJailbreakInference{}
+	}
+
+	piiInference := &ModernBertPIIInference{}
+
 	return &Classifier{
+		categoryInference:  categoryInference,
+		jailbreakInference: jailbreakInference,
+		piiInference:       piiInference,
+
 		Config:               cfg,
 		CategoryMapping:      categoryMapping,
 		PIIMapping:           piiMapping,
@@ -117,13 +184,7 @@ func (c *Classifier) CheckForJailbreak(text string) (bool, string, float32, erro
 	var err error
 
 	start := time.Now()
-	if c.Config.PromptGuard.UseModernBERT {
-		// Use ModernBERT jailbreak classifier
-		result, err = candle_binding.ClassifyModernBertJailbreakText(text)
-	} else {
-		// Use linear jailbreak classifier
-		result, err = candle_binding.ClassifyJailbreakText(text)
-	}
+	result, err = c.jailbreakInference.Classify(text)
 	metrics.RecordClassifierLatency("jailbreak", time.Since(start).Seconds())
 
 	if err != nil {
@@ -200,13 +261,7 @@ func (c *Classifier) ClassifyCategory(text string) (string, float64, error) {
 	var err error
 
 	start := time.Now()
-	if c.Config.Classifier.CategoryModel.UseModernBERT {
-		// Use ModernBERT classifier
-		result, err = candle_binding.ClassifyModernBertText(text)
-	} else {
-		// Use linear classifier
-		result, err = candle_binding.ClassifyText(text)
-	}
+	result, err = c.categoryInference.Classify(text)
 	metrics.RecordClassifierLatency("category", time.Since(start).Seconds())
 
 	if err != nil {
@@ -249,7 +304,7 @@ func (c *Classifier) ClassifyPII(text string) ([]string, error) {
 	// Use ModernBERT PII token classifier for entity detection
 	configPath := fmt.Sprintf("%s/config.json", c.Config.Classifier.PIIModel.ModelID)
 	start := time.Now()
-	tokenResult, err := candle_binding.ClassifyModernBertPIITokens(text, configPath)
+	tokenResult, err := c.piiInference.ClassifyTokens(text, configPath)
 	metrics.RecordClassifierLatency("pii", time.Since(start).Seconds())
 	if err != nil {
 		return nil, fmt.Errorf("PII token classification error: %w", err)
@@ -331,7 +386,7 @@ func (c *Classifier) AnalyzeContentForPII(contentList []string) (bool, []PIIAnal
 		// Use ModernBERT PII token classifier for detailed analysis
 		configPath := fmt.Sprintf("%s/config.json", c.Config.Classifier.PIIModel.ModelID)
 		start := time.Now()
-		tokenResult, err := candle_binding.ClassifyModernBertPIITokens(content, configPath)
+		tokenResult, err := c.piiInference.ClassifyTokens(content, configPath)
 		metrics.RecordClassifierLatency("pii", time.Since(start).Seconds())
 		if err != nil {
 			log.Printf("Error analyzing content %d: %v", i, err)