Added unit test to test #5334 (#5341)

quickwit/quickwit-storage/src/split_cache/split_table.rs

@@ -452,13 +452,16 @@ pub(crate) struct DownloadOpportunity {
 #[cfg(test)]
 mod tests {
     use std::num::NonZeroU32;
+    use std::sync::Arc;
 
     use bytesize::ByteSize;
     use quickwit_common::uri::Uri;
     use quickwit_config::SplitCacheLimits;
     use ulid::Ulid;
 
-    use crate::split_cache::split_table::{DownloadOpportunity, SplitTable};
+    use crate::split_cache::split_table::{
+        CandidateSplit, DownloadOpportunity, SplitInfo, SplitKey, SplitTable, Status,
+    };
 
     const TEST_STORAGE_URI: &str = "s3://test";
 
@@ -667,4 +670,38 @@ mod tests {
             );
         }
     }
+
+    // Unit test for #5334
+    #[test]
+    fn test_split_inserted_is_the_worst_candidate_5334() {
+        let mut split_table = SplitTable::with_limits_and_existing_splits(
+            SplitCacheLimits {
+                max_num_bytes: ByteSize::mb(10),
+                max_num_splits: NonZeroU32::new(2).unwrap(),
+                num_concurrent_downloads: NonZeroU32::new(1).unwrap(),
+                max_file_descriptors: NonZeroU32::new(100).unwrap(),
+            },
+            Default::default(),
+        );
+        for i in (0u128..=super::MAX_NUM_CANDIDATES as u128).rev() {
+            let split_ulid = Ulid(i);
+            let candidate_split = CandidateSplit {
+                storage_uri: Uri::for_test(TEST_STORAGE_URI),
+                split_ulid,
+                living_token: Arc::new(()),
+            };
+            let split_info = SplitInfo {
+                split_key: SplitKey {
+                    last_accessed: 0u64,
+                    split_ulid,
+                },
+                status: Status::Candidate(candidate_split),
+            };
+            split_table.insert(split_info);
+        }
+        assert_eq!(
+            split_table.candidate_splits.len(),
+            super::MAX_NUM_CANDIDATES
+        );
+    }
 }