[storage] Implement Drop for Pack

crates/primitives/src/key_ptr.rs

@@ -41,4 +41,9 @@ impl KeyPtr {
         self.key += old_shift;
         &self.key
     }
+
+    /// Returns the underlying offset key.
+    pub fn key(&self) -> &Key {
+        &self.key
+    }
 }

crates/storage/src/collections/binary_heap/tests.rs

@@ -255,6 +255,16 @@ fn drop_works() {
 
         assert!(setup_result.is_ok(), "setup should not panic");
 
+        let contract_id = ink_env::test::get_current_contract_account_id::<
+            ink_env::DefaultEnvironment,
+        >()
+        .expect("Cannot get contract id");
+        let used_cells = ink_env::test::count_used_storage_cells::<
+            ink_env::DefaultEnvironment,
+        >(&contract_id)
+        .expect("Used cells must be returned");
+        assert_eq!(used_cells, 0);
+
         let _ =
             <BinaryHeap<u8> as SpreadLayout>::pull_spread(&mut KeyPtr::from(root_key));
         Ok(())

crates/storage/src/collections/hashmap/tests.rs

@@ -352,3 +352,38 @@ fn storage_is_cleared_completely_after_pull_lazy() {
     })
     .unwrap()
 }
+
+#[test]
+#[should_panic(expected = "storage entry was empty")]
+fn drop_works() {
+    ink_env::test::run_test::<ink_env::DefaultEnvironment, _>(|_| {
+        let root_key = Key::from([0x42; 32]);
+
+        // if the setup panics it should not cause the test to pass
+        let setup_result = std::panic::catch_unwind(|| {
+            let hmap = filled_hmap();
+            SpreadLayout::push_spread(&hmap, &mut KeyPtr::from(root_key));
+            let _ = <StorageHashMap<u8, i32> as SpreadLayout>::pull_spread(
+                &mut KeyPtr::from(root_key),
+            );
+            // hmap is dropped which should clear the cells
+        });
+        assert!(setup_result.is_ok(), "setup should not panic");
+
+        let contract_id = ink_env::test::get_current_contract_account_id::<
+            ink_env::DefaultEnvironment,
+        >()
+        .expect("Cannot get contract id");
+        let used_cells = ink_env::test::count_used_storage_cells::<
+            ink_env::DefaultEnvironment,
+        >(&contract_id)
+        .expect("used cells must be returned");
+        assert_eq!(used_cells, 0);
+
+        let _ = <StorageHashMap<u8, i32> as SpreadLayout>::pull_spread(
+            &mut KeyPtr::from(root_key),
+        );
+        Ok(())
+    })
+    .unwrap()
+}

crates/storage/src/collections/stash/tests.rs

@@ -781,3 +781,37 @@ fn storage_is_cleared_completely_after_pull_lazy() {
     })
     .unwrap()
 }
+
+#[test]
+#[should_panic(expected = "storage entry was empty")]
+fn drop_works() {
+    ink_env::test::run_test::<ink_env::DefaultEnvironment, _>(|_| {
+        let root_key = Key::from([0x42; 32]);
+
+        // if the setup panics it should not cause the test to pass
+        let setup_result = std::panic::catch_unwind(|| {
+            let stash = create_holey_stash();
+            SpreadLayout::push_spread(&stash, &mut KeyPtr::from(root_key));
+            let _ = <StorageStash<u8> as SpreadLayout>::pull_spread(&mut KeyPtr::from(
+                root_key,
+            ));
+            // stash is dropped which should clear the cells
+        });
+        assert!(setup_result.is_ok(), "setup should not panic");
+
+        let contract_id = ink_env::test::get_current_contract_account_id::<
+            ink_env::DefaultEnvironment,
+        >()
+        .expect("Cannot get contract id");
+        let used_cells = ink_env::test::count_used_storage_cells::<
+            ink_env::DefaultEnvironment,
+        >(&contract_id)
+        .expect("used cells must be returned");
+        assert_eq!(used_cells, 0);
+
+        let _ =
+            <StorageStash<u8> as SpreadLayout>::pull_spread(&mut KeyPtr::from(root_key));
+        Ok(())
+    })
+    .unwrap()
+}