🛡️ Sentry: [test coverage improvement] (#745)

* 🛡️ Sentry: [test coverage improvement]

💡 What: Fixed a bug where `take_while` was dropping the final required listing for calculating list totals. Implemented a deterministic test suite for `get_cheapest_listing` inside `list_summary.rs`.
🎯 Why: A previous bug pattern was identified where iterators using `take_while` to accumulate quantity check incorrectly *after* the quantity was accumulated. This meant that the final listing that fulfills the quantity requirement gets incorrectly filtered out. This directly improves the UI presentation of missing quantities on lists.
📊 Impact: Covered `get_cheapest_listing` logic inside `ultros-app/src/components/list/list_summary.rs`.
🔬 Verification: Run `cargo test -p ultros-app components::list::list_summary`

Co-authored-by: akarras <1495237+akarras@users.noreply.github.com>

* 🛡️ Sentry: [test coverage improvement]

💡 What: Fixed a bug where `take_while` was dropping the final required listing for calculating list totals. Implemented a deterministic test suite for `get_cheapest_listing` inside `list_summary.rs`.
🎯 Why: A previous bug pattern was identified where iterators using `take_while` to accumulate quantity check incorrectly *after* the quantity was accumulated. This meant that the final listing that fulfills the quantity requirement gets incorrectly filtered out. This directly improves the UI presentation of missing quantities on lists.
📊 Impact: Covered `get_cheapest_listing` logic inside `ultros-app/src/components/list/list_summary.rs`.
🔬 Verification: Run `cargo test -p ultros-app components::list::list_summary`

Co-authored-by: akarras <1495237+akarras@users.noreply.github.com>

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: akarras

.jules/sentry.md

@@ -1,3 +1,4 @@
 ## 2024-05-30 - [Leptos UI Value Testing] Learning: Testing frontend UI formatters and logic filters avoids silent UX failures. Action: Always add comprehensive tests for analysis formatters in Leptos/Axum apps since they heavily influence users' view on data.
 ## 2024-05-30 - [Robust Zero IQR Stats Analysis] Learning: When computing averages on recent sales logic and analyzing market values, the Interquartile Range (IQR) method encounters edge cases like an IQR of 0 if items map to the exact same price. Action: Ensure outlier calculation functions include specific validation for a zero-IQR path to prevent crashes or silent filtering errors.
 ## 2024-06-01 - [take_while bug in pricing] Learning: When computing cheapest prices by taking elements from a list up to a target quantity, simply using `current_quantity <= quantity_needed` in a `take_while` can drop the last listing needed to fulfill an order if that listing pushes the quantity over the target. Action: When summing quantities using iterator methods like `take_while`, use the quantity accumulated *before* adding the current item's quantity for the condition check to ensure the boundary item is included.
+## 2024-06-01 - [take_while fix in list_summary.rs] Learning: Found the same take_while dropping boundary elements in list_summary.rs as was found in recipepricecheck previously. Action: Applied the same logic (storing the condition variable before incrementing) to list_summary.rs. The components test confirms boundary inclusion correctly.

ultros-frontend/ultros-app/src/components/list/list_summary.rs

@@ -40,9 +40,10 @@ fn get_cheapest_listing(
                 true
             }
         })
-        .take_while(|listings| {
-            current_quantity += listings.quantity;
-            current_quantity <= quantity_needed
+        .take_while(|listing| {
+            let needed_more = current_quantity < quantity_needed;
+            current_quantity += listing.quantity;
+            needed_more
         })
         .collect::<Vec<_>>()
 }
@@ -304,3 +305,52 @@ pub fn ListSummary(items: Vec<(ListItem, Vec<ActiveListing>)>) -> impl IntoView
     }
     .into_any()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::NaiveDate;
+
+    fn mock_listing(id: i32, price_per_unit: i32, quantity: i32, hq: bool) -> ActiveListing {
+        ActiveListing {
+            id,
+            world_id: 1,
+            item_id: 1,
+            retainer_id: 1,
+            price_per_unit,
+            quantity,
+            hq,
+            timestamp: NaiveDate::from_ymd_opt(2023, 1, 1)
+                .unwrap()
+                .and_hms_opt(0, 0, 0)
+                .unwrap(),
+        }
+    }
+
+    #[test]
+    fn test_get_cheapest_listing_exact_quantity() {
+        let listings = vec![
+            mock_listing(1, 100, 5, false),
+            mock_listing(2, 200, 5, false),
+            mock_listing(3, 300, 5, false),
+        ];
+        let result = get_cheapest_listing(listings, 10, None);
+        assert_eq!(result.len(), 2);
+        assert_eq!(result[0].id, 1);
+        assert_eq!(result[1].id, 2);
+    }
+
+    #[test]
+    fn test_get_cheapest_listing_exceeds_quantity() {
+        let listings = vec![
+            mock_listing(1, 100, 5, false),
+            mock_listing(2, 200, 10, false),
+            mock_listing(3, 300, 5, false),
+        ];
+        // We need 12. We take the 5 from id=1, and we need 7 more, so we take the 10 from id=2.
+        let result = get_cheapest_listing(listings, 12, None);
+        assert_eq!(result.len(), 2);
+        assert_eq!(result[0].id, 1);
+        assert_eq!(result[1].id, 2);
+    }
+}