UPDATE: Skeleton for the garbage collector

base/src/garbage_collector.rs

@@ -0,0 +1,12 @@
+use crate::model::Model;
+
+// The gc (Garbage Collector) cleans up leftover elements in the workbook:
+// * Strings that are no longe reachable
+// * Styles that are no longer reachable
+// * ...
+
+impl Model {
+    pub(crate) fn gc(&mut self) -> Result<(), String> {
+        todo!()
+    }
+}

base/src/lib.rs

@@ -50,6 +50,7 @@ mod implicit_intersection;
 mod units;
 mod utils;
 mod workbook;
+mod garbage_collector;
 
 #[cfg(test)]
 mod test;

base/src/test/mod.rs

@@ -53,3 +53,4 @@ mod test_frozen_rows_and_columns;
 mod test_get_cell_content;
 mod test_percentage;
 mod test_today;
+mod test_gc;

base/src/test/test_gc.rs

@@ -0,0 +1,22 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::test::util::new_empty_model;
+
+#[test]
+fn test_empty_model() {
+    let mut model = new_empty_model();
+    // set a string
+    model._set("A1", "Hello");
+    assert_eq!(model.shared_strings.len(), 1);
+    // calling the gc doesn't do anything
+    model.gc().unwrap();
+    assert_eq!(model.shared_strings.len(), 1);
+
+    // If we delete the cell the string is still in the list
+    model.delete_cell(0, 1, 1).unwrap();
+    assert_eq!(model.shared_strings.len(), 1);
+
+    // after the gc the string is no longer present
+    model.gc().unwrap();
+    assert_eq!(model.shared_strings.len(), 0);
+}