fix tests

nexus/src/app/background/init.rs

@@ -729,7 +729,9 @@ fn init_dns(
 
 #[cfg(test)]
 pub mod test {
+    use crate::app::saga::SagaStarter;
     use dropshot::HandlerTaskMode;
+    use futures::FutureExt;
     use nexus_db_model::DnsGroup;
     use nexus_db_queries::context::OpContext;
     use nexus_db_queries::db::datastore::DnsVersionUpdateBuilder;
@@ -738,9 +740,39 @@ pub mod test {
     use nexus_types::internal_api::params as nexus_params;
     use omicron_test_utils::dev::poll;
     use std::net::SocketAddr;
+    use std::sync::atomic::AtomicU64;
+    use std::sync::atomic::Ordering;
     use std::time::Duration;
     use tempfile::TempDir;
 
+    /// Used by various tests of tasks that kick off sagas
+    pub(crate) struct NoopSagaStarter {
+        count: AtomicU64,
+    }
+
+    impl NoopSagaStarter {
+        pub(crate) fn new() -> Self {
+            Self { count: AtomicU64::new(0) }
+        }
+
+        pub(crate) fn count_reset(&self) -> u64 {
+            self.count.swap(0, Ordering::SeqCst)
+        }
+    }
+
+    impl SagaStarter for NoopSagaStarter {
+        fn saga_start(
+            &self,
+            _: steno::SagaDag,
+        ) -> futures::prelude::future::BoxFuture<
+            '_,
+            Result<(), omicron_common::api::external::Error>,
+        > {
+            let _ = self.count.fetch_add(1, Ordering::SeqCst);
+            async { Ok(()) }.boxed()
+        }
+    }
+
     type ControlPlaneTestContext =
         nexus_test_utils::ControlPlaneTestContext<crate::Server>;
 

nexus/src/app/background/tasks/region_replacement.rs

@@ -198,6 +198,7 @@ impl BackgroundTask for RegionReplacementDetector {
 #[cfg(test)]
 mod test {
     use super::*;
+    use crate::app::background::init::test::NoopSagaStarter;
     use nexus_db_model::RegionReplacement;
     use nexus_test_utils_macros::nexus_test;
     use uuid::Uuid;
@@ -216,10 +217,9 @@ mod test {
             datastore.clone(),
         );
 
-        let mut task = RegionReplacementDetector::new(
-            datastore.clone(),
-            nexus.saga_starter(),
-        );
+        let starter = Arc::new(NoopSagaStarter::new());
+        let mut task =
+            RegionReplacementDetector::new(datastore.clone(), starter.clone());
 
         // Noop test
         let result = task.activate(&opctx).await;
@@ -250,8 +250,6 @@ mod test {
             })
         );
 
-        // XXX-dap
-        // saga_request_rx.try_recv().unwrap();
-        todo!();
+        assert_eq!(starter.count_reset(), 1);
     }
 }