add tests, serial, lib, etc (3h1m)

tests/basic_boot.rs

@@ -0,0 +1,32 @@
+// Basic boot test
+
+#![no_std]
+#![no_main]
+#![feature(custom_test_frameworks)]
+#![test_runner(donald::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+
+#[no_mangle] // don't mangle the name of this function
+pub extern "C" fn _start() -> ! {
+    test_main();
+
+    loop {}
+}
+
+fn test_runner(tests: &[&dyn Fn()]) {
+    unimplemented!();
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    donald::test_panic_handler(info)
+}
+
+use donald::println;
+
+#[test_case]
+fn test_println() {
+    println!("test_println output");
+}