Return the username in a separate service

This allows us to use a service implementation which
returns a dummy user during development and the actual authenticated
user during production.  It also simplifies tests.

service_impl/src/lib.rs

@@ -33,27 +33,35 @@ where
     }
 }
 
-pub struct PermissionServiceImpl<PermissionDao>
+pub struct PermissionServiceImpl<PermissionDao, UserService>
 where
     PermissionDao: dao::PermissionDao + Send + Sync,
+    UserService: service::UserService + Send + Sync,
 {
     permission_dao: Arc<PermissionDao>,
+    user_service: Arc<UserService>,
 }
-impl<PermissionDao> PermissionServiceImpl<PermissionDao>
+impl<PermissionDao, UserService> PermissionServiceImpl<PermissionDao, UserService>
 where
     PermissionDao: dao::PermissionDao + Send + Sync,
+    UserService: service::UserService + Send + Sync,
 {
-    pub fn new(permission_dao: Arc<PermissionDao>) -> Self {
-        Self { permission_dao }
+    pub fn new(permission_dao: Arc<PermissionDao>, user_service: Arc<UserService>) -> Self {
+        Self {
+            permission_dao,
+            user_service,
+        }
     }
 }
 
-impl<PermissionDao> service::PermissionService for PermissionServiceImpl<PermissionDao>
+impl<PermissionDao, UserService> service::PermissionService
+    for PermissionServiceImpl<PermissionDao, UserService>
 where
     PermissionDao: dao::PermissionDao + Send + Sync,
+    UserService: service::UserService + Send + Sync,
 {
     async fn check_permission(&self, privilege: &str) -> Result<(), service::ServiceError> {
-        let current_user = self.current_user().await?;
+        let current_user = self.user_service.current_user().await?;
         if self
             .permission_dao
             .has_privilege(current_user.as_ref(), privilege)
@@ -64,7 +72,11 @@ where
             Err(service::ServiceError::Forbidden)
         }
     }
+}
 
+pub struct UserServiceDev;
+
+impl service::UserService for UserServiceDev {
     async fn current_user(&self) -> Result<Arc<str>, service::ServiceError> {
         Ok("DEVUSER".into())
     }