unit testing for vga

Cargo.toml

@@ -19,6 +19,7 @@ bootloader = "0.9"
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"
+uart_16550 = "0.2.0"
 
 [dependencies.lazy_static]
 version = "1.0"
@@ -26,5 +27,13 @@ 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-args = [
+  "-device",
+  "isa-debug-exit,iobase=0xf4,iosize=0x04",
+  "-serial",
+  "stdio",
+  "-display",
+  "none",
+]
 test-success-exit-code = 33 # (0x10 << 1) | 1 = 33
+test-timeout = "300" # in seconds

src/main.rs

@@ -7,6 +7,22 @@
 use core::panic::PanicInfo;
 
 mod vga_buffer;
+mod serial;
+
+pub trait Testable {
+    fn run(&self) -> ();
+}
+
+impl<T> Testable for T
+where
+    T: Fn(),
+{
+    fn run(&self) -> () {
+        serial_print!("{}...\t", core::any::type_name::<T>());
+        self();
+        serial_println!("[ok]");
+    }
+}
 
 static HELLO: &[u8] = b"Hello toto :3";
 
@@ -38,7 +54,8 @@ pub extern "C" fn _start() -> ! {
     loop {}
 }
 
-// called on panic
+// panic handler
+#[cfg(not(test))]
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
@@ -46,12 +63,23 @@ fn panic(info: &PanicInfo) -> ! {
     loop {}
 }
 
+// panic handler in test mode
 #[cfg(test)]
-pub fn test_runner(tests: &[&dyn Fn()]) {
-    println!("Running {} tests", tests.len());
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+
+    loop {}
+}
+
+#[cfg(test)]
+pub fn test_runner(tests: &[&dyn Testable]) {
+    serial_println!("Running {} tests", tests.len());
 
     for test in tests {
-        test();
+        test.run();
     }
 
     exit_qemu(QemuExitCode::Success);
@@ -59,7 +87,5 @@ pub fn test_runner(tests: &[&dyn Fn()]) {
 
 #[test_case]
 fn trivial_assertion() {
-    print!("asserzione triviale... ");
     assert_eq!(1, 1);
-    println!("[ok]");
 }

src/serial.rs

@@ -0,0 +1,35 @@
+use uart_16550::SerialPort;
+use spin::Mutex;
+use lazy_static::lazy_static;
+
+lazy_static! {
+    pub static ref SERIAL1: Mutex<SerialPort> = {
+        let mut serial_port = unsafe { SerialPort::new(0x3F8) };
+        serial_port.init();
+        Mutex::new(serial_port)
+    };
+}
+
+#[doc(hidden)]
+pub fn _print(args: ::core::fmt::Arguments) {
+    use core::fmt::Write;
+    SERIAL1.lock().write_fmt(args).expect("Printing to serial failed :(");
+}
+
+// prints to the host through the serial interface
+#[macro_export]
+macro_rules! serial_print {
+    ($($arg:tt)*) => {
+        $crate::serial::_print(format_args!($($arg)*));
+    };
+}
+
+// prints to the host through the serial interface
+// appending a newline
+#[macro_export]
+macro_rules! serial_println {
+    () => ($crate::serial_print!("\n"));
+    ($fmt:expr) => ($crate::serial_print!(concat!($fmt, "\n")));
+    ($fmt:expr, $($arg:tt)*) => ($crate::serial_print!(
+        concat!($fmt, "\n"), $($arg)*));
+}

src/vga_buffer.rs

@@ -155,3 +155,28 @@ impl Writer {
     }
 }
 
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("test_println_many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    let s = "loss and gain is the same";
+    println!("{}", s);
+
+    for (i, c) in s.chars().enumerate() {
+        let screen_char = WRITER.lock()
+            .buffer
+            .chars[BUFFER_HEIGHT - 2][i]
+            .read();
+        assert_eq!(char::from(screen_char.ascii_carachter), c);
+    }
+}