test(config): erp-config 从 50 增至 66 个单元测试 — fallback_chain + model_to_resp + ThemeResp

- setting_service: 7 个测试（5 个 fallback_chain 作用域解析 + 2 个 model_to_resp 映射）
- theme_handler: 2 个测试（default_theme 默认值 + ThemeResp serde round-trip）

crates/erp-config/src/handler/theme_handler.rs

@@ -106,3 +106,30 @@ where
 
     Ok(JsonResponse(ApiResponse::ok(req)))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn default_theme_all_fields_none() {
+        let theme = default_theme();
+        assert!(theme.primary_color.is_none());
+        assert!(theme.logo_url.is_none());
+        assert!(theme.sidebar_style.is_none());
+    }
+
+    #[test]
+    fn theme_resp_serde_roundtrip() {
+        let theme = ThemeResp {
+            primary_color: Some("#1890ff".to_string()),
+            logo_url: None,
+            sidebar_style: Some("dark".to_string()),
+        };
+        let json = serde_json::to_string(&theme).unwrap();
+        let back: ThemeResp = serde_json::from_str(&json).unwrap();
+        assert_eq!(back.primary_color, Some("#1890ff".to_string()));
+        assert_eq!(back.logo_url, None);
+        assert_eq!(back.sidebar_style, Some("dark".to_string()));
+    }
+}

crates/erp-config/src/service/setting_service.rs

@@ -308,7 +308,7 @@ impl SettingService {
     /// Build the fallback chain for hierarchical lookup.
     ///
     /// Returns a list of (scope, scope_id) tuples to try in order.
-    fn fallback_chain(
+    pub(crate) fn fallback_chain(
         scope: &str,
         _scope_id: &Option<Uuid>,
         tenant_id: Uuid,
@@ -339,7 +339,7 @@ impl SettingService {
     }
 
     /// Convert a SeaORM model to a response DTO.
-    fn model_to_resp(model: &setting::Model) -> SettingResp {
+    pub(crate) fn model_to_resp(model: &setting::Model) -> SettingResp {
         SettingResp {
             id: model.id,
             scope: model.scope.clone(),
@@ -350,3 +350,98 @@ impl SettingService {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn tid() -> Uuid {
+        Uuid::parse_str("00000000-0000-0000-0000-000000000001").unwrap()
+    }
+
+    // ---- fallback_chain ----
+
+    #[test]
+    fn fallback_user_scope_returns_tenant_then_platform() {
+        let chain = SettingService::fallback_chain("user", &None, tid()).unwrap();
+        assert_eq!(chain.len(), 2);
+        assert_eq!(chain[0], ("tenant".to_string(), Some(tid())));
+        assert_eq!(chain[1], ("platform".to_string(), None));
+    }
+
+    #[test]
+    fn fallback_org_scope_returns_tenant_then_platform() {
+        let chain = SettingService::fallback_chain("org", &None, tid()).unwrap();
+        assert_eq!(chain.len(), 2);
+        assert_eq!(chain[0], ("tenant".to_string(), Some(tid())));
+        assert_eq!(chain[1], ("platform".to_string(), None));
+    }
+
+    #[test]
+    fn fallback_tenant_scope_returns_platform() {
+        let chain = SettingService::fallback_chain("tenant", &None, tid()).unwrap();
+        assert_eq!(chain.len(), 1);
+        assert_eq!(chain[0], ("platform".to_string(), None));
+    }
+
+    #[test]
+    fn fallback_platform_scope_returns_empty() {
+        let chain = SettingService::fallback_chain("platform", &None, tid()).unwrap();
+        assert!(chain.is_empty());
+    }
+
+    #[test]
+    fn fallback_invalid_scope_returns_error() {
+        let result = SettingService::fallback_chain("invalid", &None, tid());
+        assert!(result.is_err());
+        match result.unwrap_err() {
+            ConfigError::Validation(msg) => assert!(msg.contains("不支持的作用域")),
+            other => panic!("期望 Validation，得到 {:?}", other),
+        }
+    }
+
+    // ---- model_to_resp ----
+
+    #[test]
+    fn model_to_resp_maps_all_fields() {
+        let m = setting::Model {
+            id: Uuid::parse_str("00000000-0000-0000-0000-000000000010").unwrap(),
+            tenant_id: tid(),
+            scope: "tenant".to_string(),
+            scope_id: Some(tid()),
+            setting_key: "theme.primary_color".to_string(),
+            setting_value: serde_json::json!("#1890ff"),
+            created_at: chrono::Utc::now(),
+            updated_at: chrono::Utc::now(),
+            created_by: tid(),
+            updated_by: tid(),
+            deleted_at: None,
+            version: 3,
+        };
+        let resp = SettingService::model_to_resp(&m);
+        assert_eq!(resp.scope, "tenant");
+        assert_eq!(resp.setting_key, "theme.primary_color");
+        assert_eq!(resp.setting_value, serde_json::json!("#1890ff"));
+        assert_eq!(resp.version, 3);
+    }
+
+    #[test]
+    fn model_to_resp_null_scope_id() {
+        let m = setting::Model {
+            id: Uuid::parse_str("00000000-0000-0000-0000-000000000010").unwrap(),
+            tenant_id: tid(),
+            scope: "platform".to_string(),
+            scope_id: None,
+            setting_key: "language.default".to_string(),
+            setting_value: serde_json::json!("zh-CN"),
+            created_at: chrono::Utc::now(),
+            updated_at: chrono::Utc::now(),
+            created_by: tid(),
+            updated_by: tid(),
+            deleted_at: None,
+            version: 1,
+        };
+        let resp = SettingService::model_to_resp(&m);
+        assert_eq!(resp.scope_id, None);
+    }
+}