fix windows build continued

tauri/tests/app/main.rs

@@ -0,0 +1,15 @@
+//! The tests of the desktop app. They are integration tests, in a single binary, rather than unit
+//! tests: on Windows, only test binaries can be given the manifest that the app needs to start
+//! (see `build.rs`).
+
+mod commands;
+mod store;
+mod workspace;
+
+use gpx_studio_desktop_lib::state::AppState;
+
+/// An engine that keeps its data in a directory of its own, and has nobody to tell.
+fn temporary_state() -> AppState {
+    let directory = std::env::temp_dir().join(format!("gpx-studio-{}", uuid::Uuid::new_v4()));
+    AppState::open(directory, std::sync::Arc::new(|_, _| {})).expect("the storage can be opened")
+}