Support http client middlewareing

config.go

@@ -36,7 +36,9 @@ type ClientConfig struct {
 	APIVersion           string // required when APIType is APITypeAzure or APITypeAzureAD
 	AssistantVersion     string
 	AzureModelMapperFunc func(model string) string // replace model to azure deployment name func
-	HTTPClient           *http.Client
+	HTTPClient           interface {
+		Do(req *http.Request) (*http.Response, error)
+	}
 
 	EmptyMessagesLimit uint
 }