Add integration test

As mentioned upstream[^1] the integration tests aren't able to use
cdylib crate types so "lib" was added to the list of crate types.

To not having to repeat the plugin interface types for Rust in the
integration test they were made public in the library.

The integration test needs a running MQTT server to which it will
connect. That way the full functionality (except for mstarConfigure with
its UI) can be tested.

[^1]: rust-lang/cargo#6659 (comment)

Author: ServiusHack

Cargo.lock

@@ -9,5 +9,8 @@ env_logger = "0.10.1"
 rumqttc = "0.23.0"
 slint = "1.3.0"
 
+[dev-dependencies]
+mockall = "0.11.4"
+
 [lib]
-crate-type=["cdylib"]
+crate-type=["lib", "cdylib"]

Cargo.toml

@@ -1,7 +1,7 @@
 #![allow(non_snake_case)]
 
 mod mqtt;
-mod plugin_interface_v2;
+pub mod plugin_interface_v2;
 
 use core::ffi::{c_char, c_double, c_int};
 use log::{debug, error, warn};

src/lib.rs

@@ -6,15 +6,17 @@
 
 use core::ffi::{c_char, c_float, c_void};
 
-type ListPlayersCallbackFunction = extern "C" fn(*const c_char, *const c_void);
-type ListPlayersFunction = extern "C" fn(*const c_char, ListPlayersCallbackFunction, *const c_void);
-type PlayFunction = extern "C" fn(*const c_char);
-type StopFunction = extern "C" fn(*const c_char);
-type NextFunction = extern "C" fn(*const c_char);
-type PreviousFunction = extern "C" fn(*const c_char);
-type ListTracksCallbackFunction = extern "C" fn(*const c_char, *const c_char, *const c_void);
-type ListTracksFunction = extern "C" fn(*const c_char, ListTracksCallbackFunction, *const c_void);
-type SetTrackVolumeFunction = extern "C" fn(*const c_char, *const c_char, c_float);
+pub type ListPlayersCallbackFunction = extern "C" fn(*const c_char, *const c_void);
+pub type ListPlayersFunction =
+    extern "C" fn(*const c_char, ListPlayersCallbackFunction, *const c_void);
+pub type PlayFunction = extern "C" fn(*const c_char);
+pub type StopFunction = extern "C" fn(*const c_char);
+pub type NextFunction = extern "C" fn(*const c_char);
+pub type PreviousFunction = extern "C" fn(*const c_char);
+pub type ListTracksCallbackFunction = extern "C" fn(*const c_char, *const c_char, *const c_void);
+pub type ListTracksFunction =
+    extern "C" fn(*const c_char, ListTracksCallbackFunction, *const c_void);
+pub type SetTrackVolumeFunction = extern "C" fn(*const c_char, *const c_char, c_float);
 
 #[repr(C)]
 #[derive(Clone)]