Merge PR #5654: Count tool: deleting an earlier count group keeps the active group (#5653)

crates/engine/src/analysis_cmds.rs

@@ -856,7 +856,9 @@ fn count_delete_group(s: &mut Session, p: &Value) -> Result<Value> {
     s.edit("Delete Count Group", |d, _| {
         d.measurement.count_groups.remove(g);
         let n = d.measurement.count_groups.len();
-        d.measurement.active_count_group = d.measurement.active_count_group.min(n.saturating_sub(1));
+        // Removing a group before the active one shifts it down a slot.
+        let a = d.measurement.active_count_group;
+        d.measurement.active_count_group = (if g < a { a - 1 } else { a }).min(n.saturating_sub(1));
         Ok(())
     })?;
     Ok(count_json(doc(s)?.as_ref()))

crates/engine/src/analysis_cmds/tests.rs

@@ -291,6 +291,27 @@ fn count_groups_markers_and_undo() {
     assert!(s.execute("count.add", json!({"x": 1})).is_err());
 }
 
+#[test]
+fn deleting_an_earlier_count_group_keeps_the_active_group() {
+    let mut s = session(100, 100, 8);
+    s.execute("count.add", json!({"x": 10, "y": 10})).unwrap();
+    for _ in 0..3 {
+        s.execute("count.newGroup", json!({})).unwrap();
+    }
+    s.execute("count.setGroup", json!({"group": 2})).unwrap();
+    let r = s.execute("count.deleteGroup", json!({"group": 0})).unwrap();
+    assert_eq!(r["activeGroup"], 1);
+    assert_eq!(r["groups"][1]["name"], "Count Group 3");
+    // A later group leaves the active index alone.
+    let r = s.execute("count.deleteGroup", json!({"group": 2})).unwrap();
+    assert_eq!(r["activeGroup"], 1);
+    assert_eq!(r["groups"][1]["name"], "Count Group 3");
+    // Deleting the active last group selects the new last group.
+    let r = s.execute("count.deleteGroup", json!({})).unwrap();
+    assert_eq!(r["activeGroup"], 0);
+    assert_eq!(r["groups"][0]["name"], "Count Group 2");
+}
+
 #[test]
 fn log_delete_and_csv_export() {
     let mut s = session(10, 10, 8);