diff --git a/federate/federate-core/src/lib.rs b/federate/federate-core/src/lib.rs
index b96250b..bad7f94 100644
--- a/federate/federate-core/src/lib.rs
+++ b/federate/federate-core/src/lib.rs
@@ -54,6 +54,14 @@ pub trait Federate: Sync + Send {
     /// add repository isntance
     async fn create_repository(&self, f: &AddRepository<'_>) -> Result<(), Self::Error>;
 
+    /// check if a repository exists.
+    async fn repository_exists(
+        &self,
+        name: &str,
+        owner: &str,
+        hostname: &str,
+    ) -> Result<bool, Self::Error>;
+
     /// delete user
     async fn delete_user(&self, username: &str, hostname: &str) -> Result<(), Self::Error>;
 
diff --git a/federate/federate-core/src/tests.rs b/federate/federate-core/src/tests.rs
index d966c7a..df9a268 100644
--- a/federate/federate-core/src/tests.rs
+++ b/federate/federate-core/src/tests.rs
@@ -42,7 +42,15 @@ pub async fn adding_forge_works<'a, T: Federate>(
         .unwrap());
 
     // add repository
+    assert!(!ff
+        .repository_exists(add_repo_msg.name, add_repo_msg.owner, add_repo_msg.hostname)
+        .await
+        .unwrap());
     ff.create_repository(&add_repo_msg).await.unwrap();
+    assert!(ff
+        .repository_exists(add_repo_msg.name, add_repo_msg.owner, add_repo_msg.hostname)
+        .await
+        .unwrap());
 
     // tar()
     ff.tar().await.unwrap();