added tests + exiting by interacting with qemu through a I/O port

.cargo/config.toml

@@ -1,6 +1,7 @@
 [unstable]
 build-std-features = ["compiler-builtins-mem"]
 build-std = ["core", "compiler_builtins"]
+panic-abort-tests = true
 
 [build]
 target = "x86_64-totos.json"

Cargo.toml

@@ -5,7 +5,7 @@ edition = "2024"
 
 [[bin]]
 name = "totos"
-test = false
+test = true
 bench = false
 
 [profile.dev]
@@ -18,7 +18,13 @@ panic = "abort" # disable stack unwinding on panic
 bootloader = "0.9"
 volatile = "0.2.6"
 spin = "0.5.2"
+x86_64 = "0.14.2"
 
 [dependencies.lazy_static]
 version = "1.0"
 features = ["spin_no_std"]
+
+# this enables exiting qemu from the guest system
+[package.metadata.bootimage]
+test-args = ["-device", "isa-debug-exit,iobase=0xf4,iosize=0x04"]
+test-success-exit-code = 33 # (0x10 << 1) | 1 = 33

src/main.rs

@@ -1,5 +1,8 @@
 #![no_std] // dont link the standard library
 #![no_main] // disable all rust-level entry points
+#![feature(custom_test_frameworks)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]
 
 use core::panic::PanicInfo;
 
@@ -7,12 +10,31 @@ mod vga_buffer;
 
 static HELLO: &[u8] = b"Hello toto :3";
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum QemuExitCode {
+    Success = 0x10,
+    Failed = 0x11,
+}
+
+pub fn exit_qemu(exit_code: QemuExitCode) {
+    use x86_64::instructions::port::Port;
+
+    unsafe {
+        let mut port = Port::new(0xF4);
+        port.write(exit_code as u32);
+    }
+}
+
 // this function is the entry point since the linker
 // looks for a function named `_start` by default
 #[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
     println!("smoking cigarettes in the shower\nwhen they get wet i just light another\n:{}", 3);
 
+    #[cfg(test)]
+    test_main();
+
     loop {}
 }
 
@@ -23,3 +45,21 @@ fn panic(info: &PanicInfo) -> ! {
 
     loop {}
 }
+
+#[cfg(test)]
+pub fn test_runner(tests: &[&dyn Fn()]) {
+    println!("Running {} tests", tests.len());
+
+    for test in tests {
+        test();
+    }
+
+    exit_qemu(QemuExitCode::Success);
+}
+
+#[test_case]
+fn trivial_assertion() {
+    print!("asserzione triviale... ");
+    assert_eq!(1, 1);
+    println!("[ok]");
+}