feat/ocw/bookkeeping (#5200)

Co-Authored-By: Kian Paimani <5588131+kianenigma@users.noreply.github.com>
Co-Authored-By: Tomasz Drwięga <tomusdrw@users.noreply.github.com>

substrate/client/executor/runtime-test/src/lib.rs

@@ -183,6 +183,12 @@ sp_core::wasm_export_functions! {
 		}
 	}
 
+
+	fn test_offchain_index_set() {
+		sp_io::offchain_index::set(b"k", b"v");
+	}
+
+
 	fn test_offchain_local_storage() -> bool {
 		let kind = sp_core::offchain::StorageKind::PERSISTENT;
 		assert_eq!(sp_io::offchain::local_storage_get(kind, b"test"), None);