feat(core): add test::test::get_ipc_response, closes #8199 (#8228)

* feat(core): Add additional functions to the

* Add documentation and cleanup the code

* Improve and add tests to helper functions

* Clean unecessary code and correct tests

* Make `Ipc` and `IpcKey` public

* Open `Ipc` with public functions

* Update core/tauri/src/test/mod.rs

Co-authored-by: Lucas Fernandes Nogueira <lucas@tauri.app>

* cleanup, change file

---------

Co-authored-by: Lucas Fernandes Nogueira <lucas@tauri.app>
Co-authored-by: Lucas Nogueira <lucas@crabnebula.dev>

.changes/get-ipc-response-test.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch:enhance
+---
+
+Added `test::get_ipc_response`.

core/tauri/src/test/mod.rs

@@ -27,7 +27,9 @@
 //! }
 //!
 //! fn main() {
-//!   let app = create_app(tauri::Builder::default());
+//!   // Use `tauri::Builder::default()` to use the default runtime rather than the `MockRuntime`;
+//!   // let app = create_app(tauri::Builder::default());
+//!   let app = create_app(tauri::test::mock_builder());
 //!   // app.run(|_handle, _event| {});
 //! }
 //!
@@ -59,6 +61,7 @@
 
 mod mock_runtime;
 pub use mock_runtime::*;
+use serde::de::DeserializeOwned;
 use serde::Serialize;
 use serde_json::Value as JsonValue;
 
@@ -82,9 +85,12 @@ use tauri_utils::{
   config::{CliConfig, Config, PatternKind, TauriConfig},
 };
 
+/// A key for an [`Ipc`] call.
 #[derive(Eq, PartialEq)]
 struct IpcKey {
+  /// callback
   callback: CallbackFn,
+  /// error callback
   error: CallbackFn,
 }
 
@@ -95,6 +101,7 @@ impl Hash for IpcKey {
   }
 }
 
+/// Structure to retrieve result of a Tauri command
 struct Ipc(Mutex<HashMap<IpcKey, Sender<std::result::Result<JsonValue, JsonValue>>>>);
 
 /// An empty [`Assets`] implementation.
@@ -227,18 +234,11 @@ pub fn mock_app() -> App<MockRuntime> {
 ///     .expect("failed to build app")
 /// }
 ///
-/// fn main() {
-///   let app = create_app(tauri::Builder::default());
-///   // app.run(|_handle, _event| {});}
-/// }
-///
-/// //#[cfg(test)]
-/// mod tests {
 /// use tauri::Manager;
-///
-///   //#[cfg(test)]
-///   fn something() {
-///     let app = super::create_app(tauri::test::mock_builder());
+/// use tauri::test::mock_builder;
+/// fn main() {
+///   // app createion with a `MockRuntime`
+///   let app = create_app(mock_builder());
 ///   let window = app.get_window("main").unwrap();
 ///
 ///   // run the `ping` command and assert it returns `pong`
@@ -256,13 +256,60 @@ pub fn mock_app() -> App<MockRuntime> {
 ///     Ok("pong")
 ///   );
 /// }
-/// }
 /// ```
 pub fn assert_ipc_response<T: Serialize + Debug>(
   window: &Window<MockRuntime>,
   payload: InvokePayload,
   expected: Result<T, T>,
 ) {
+  assert_eq!(
+    get_ipc_response(window, payload),
+    expected
+      .map(|e| serde_json::to_value(e).unwrap())
+      .map_err(|e| serde_json::to_value(e).unwrap())
+  );
+}
+
+/// The application processes the command and stops.
+///
+/// # Examples
+///
+/// ```rust
+///
+/// #[tauri::command]
+/// fn ping() -> &'static str {
+///   "pong"
+/// }
+///
+/// fn create_app<R: tauri::Runtime>(mut builder: tauri::Builder<R>) -> tauri::App<R> {
+///   builder
+///     .invoke_handler(tauri::generate_handler![ping])
+///     // remove the string argument on your app
+///     .build(tauri::generate_context!("test/fixture/src-tauri/tauri.conf.json"))
+///     .expect("failed to build app")
+/// }
+///
+/// use tauri::test::*;
+/// use tauri::Manager;
+/// let app = create_app(mock_builder());
+/// let window = app.get_window("main").unwrap();
+///
+/// // run the `ping` command and assert it returns `pong`
+/// let res = tauri::test::get_ipc_response::<String>(
+///   &window,
+///   tauri::InvokePayload {
+///     cmd: "ping".into(),
+///     tauri_module: None,
+///     callback: tauri::api::ipc::CallbackFn(0),
+///     error: tauri::api::ipc::CallbackFn(1),
+///     inner: serde_json::Value::Null,
+///   });
+/// assert_eq!(res, Ok("pong".into()))
+/// ```
+pub fn get_ipc_response<T: DeserializeOwned + Debug>(
+  window: &Window<MockRuntime>,
+  payload: InvokePayload,
+) -> Result<T, T> {
   let callback = payload.callback;
   let error = payload.error;
   let ipc = window.state::<Ipc>();
@@ -270,12 +317,10 @@ pub fn assert_ipc_response<T: Serialize + Debug>(
   ipc.0.lock().unwrap().insert(IpcKey { callback, error }, tx);
   window.clone().on_message(payload).unwrap();
 
-  assert_eq!(
-    rx.recv().unwrap(),
-    expected
-      .map(|e| serde_json::to_value(e).unwrap())
-      .map_err(|e| serde_json::to_value(e).unwrap())
-  );
+  let res: Result<JsonValue, JsonValue> = rx.recv().expect("Failed to receive result from command");
+  res
+    .map(|v| serde_json::from_value(v).unwrap())
+    .map_err(|e| serde_json::from_value(e).unwrap())
 }
 
 #[cfg(test)]