Add example for storage_address_from_base usage (#2705)

<!-- Reference any GitHub issues resolved by this PR -->

Closes #2439 

## Introduced changes

<!-- A brief description of the changes -->

Update example for `storage_address_from_base` usage in storage
cheatcodes docs

## Checklist

<!-- Make sure all of these are complete -->

- [x] Linked relevant issue
- [x] Updated relevant documentation
- [x] Added relevant tests
- [x] Performed self-review of the code
- [x] Added changes to `CHANGELOG.md`

docs/listings/snforge_advanced_features/crates/direct_storage_access/src/felts_only.cairo

@@ -1,8 +1,10 @@
 #[starknet::interface]
-pub trait ISimpleStorageContract<TState> {}
+pub trait ISimpleStorageContract<TState> {
+    fn get_value(self: @TState, key: felt252) -> felt252;
+}
 
 #[starknet::contract]
-mod SimpleStorageContract {
+pub mod SimpleStorageContract {
     use starknet::storage::Map;
 
     #[storage]
@@ -16,4 +18,9 @@ mod SimpleStorageContract {
         self.plain_felt.write(0x2137_felt252);
         self.mapping.write('some_key', 'some_value');
     }
+
+    #[external(v0)]
+    pub fn get_value(self: @ContractState, key: felt252) -> felt252 {
+        self.mapping.read(key)
+    }
 }

docs/listings/snforge_advanced_features/crates/direct_storage_access/tests/lib.cairo

@@ -1,3 +1,4 @@
 pub mod felts_only;
 pub mod complex_structures;
 pub mod storage_address;
+pub mod using_storage_address_from_base;

docs/listings/snforge_advanced_features/crates/direct_storage_access/tests/using_storage_address_from_base.cairo

@@ -0,0 +1,31 @@
+use starknet::storage::StorageAsPointer;
+use starknet::storage::StoragePathEntry;
+
+use snforge_std::{declare, ContractClassTrait, DeclareResultTrait, store, load};
+use starknet::storage_access::{storage_address_from_base};
+
+use direct_storage_access::felts_only::{
+    SimpleStorageContract, ISimpleStorageContractDispatcher, ISimpleStorageContractDispatcherTrait
+};
+
+#[test]
+fn update_mapping() {
+    let key = 0;
+    let data = 100;
+    let (contract_address, _) = declare("SimpleStorageContract")
+        .unwrap()
+        .contract_class()
+        .deploy(@array![])
+        .unwrap();
+    let dispatcher = ISimpleStorageContractDispatcher { contract_address };
+    let mut state = SimpleStorageContract::contract_state_for_testing();
+
+    let storage_address = storage_address_from_base(
+        state.mapping.entry(key).as_ptr().__storage_pointer_address__.into()
+    );
+    let storage_value: Span<felt252> = array![data.into()].span();
+    store(contract_address, storage_address.into(), storage_value);
+
+    let read_data = dispatcher.get_value(key.into());
+    assert_eq!(read_data, data, "Storage update failed")
+}

docs/src/snforge-advanced-features/storage-cheatcodes.md

@@ -49,3 +49,10 @@ And perform a test checking `load` and `store` behavior in context of those stru
 > 📝 **Note**
 >
 > The `load` cheatcode will return zeros for memory you haven't written into yet (it is a default storage value for Starknet contracts' storage).
+
+## Example with `storage_address_from_base`
+This example uses `storage_address_from_base` with entry's of the storage variable.
+
+```rust
+{{#include ../../listings/snforge_advanced_features/crates/direct_storage_access/tests/using_storage_address_from_base.cairo}}
+```