add a test

crates/index-scheduler/src/scheduler/test.rs

@@ -929,3 +929,30 @@ fn create_and_list_index() {
     ]
     "###);
 }
+
+#[test]
+fn test_scheduler_doesnt_run_with_zero_batched_tasks() {
+    let (index_scheduler, mut handle) = IndexScheduler::test_with_custom_config(vec![], |config| {
+        config.max_number_of_batched_tasks = 0;
+        None
+    });
+
+    handle.scheduler_is_down();
+
+    // Register a task
+    index_scheduler
+        .register(
+            KindWithContent::IndexCreation { index_uid: S("doggos"), primary_key: None },
+            None,
+            false,
+        )
+        .unwrap();
+    snapshot!(snapshot_index_scheduler(&index_scheduler), name: "registered_task");
+
+    handle.scheduler_is_down();
+
+    // If we restart the scheduler, it should run properly.
+    let (index_scheduler, mut handle) = handle.restart(index_scheduler, true, vec![], |_| None);
+    handle.advance_n_successful_batches(1);
+    snapshot!(snapshot_index_scheduler(&index_scheduler), name: "after_restart");
+}

crates/index-scheduler/src/test_utils.rs

@@ -118,6 +118,9 @@ impl IndexScheduler {
             (versioning::VERSION_MAJOR, versioning::VERSION_MINOR, versioning::VERSION_PATCH)
         });
 
+        // If the number of batched tasks is 0, the scheduler will not run and we can't do the init check.
+        let skip_init = options.max_number_of_batched_tasks == 0;
+
         std::fs::create_dir_all(&options.auth_path).unwrap();
         let auth_env = open_auth_store_env(&options.auth_path).unwrap();
         let index_scheduler =
@@ -126,7 +129,11 @@ impl IndexScheduler {
         // To be 100% consistent between all test we're going to start the scheduler right now
         // and ensure it's in the expected starting state.
         let breakpoint = match receiver.recv_timeout(std::time::Duration::from_secs(10)) {
+            Ok(b) if skip_init => {
+                panic!("The scheduler was not supposed to start, but it did: {b:?}.")
+            }
             Ok(b) => b,
+            Err(_) if skip_init => (Init, false),
             Err(RecvTimeoutError::Timeout) => {
                 panic!("The scheduler seems to be waiting for a new task while your test is waiting for a breakpoint.")
             }