diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..c7387d9
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,70 @@
+#![no_std]
+#![cfg_attr(test, no_main)]
+#![feature(custom_test_frameworks)]
+#![test_runner(crate::test_runner)]
+#![reexport_test_harness_main = "test_main"]
+
+use core::panic::PanicInfo;
+
+pub mod serial;
+pub mod vga_buffer;
+
+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]");
+    }
+}
+
+pub fn test_runner(tests: &[&dyn Testable]) {
+    serial_println!("Running {} tests", tests.len());
+    for test in tests {
+        test.run();
+    }
+    exit_qemu(QemuExitCode::Success);
+}
+
+pub fn test_panic_handler(info: &PanicInfo) -> ! {
+    serial_println!("[failed]\n");
+    serial_println!("Error: {}\n", info);
+    exit_qemu(QemuExitCode::Failed);
+    loop {}
+}
+
+// Entry point for `cargo test`
+#[cfg(test)]
+#[unsafe(no_mangle)]
+pub extern "C" fn _start() -> ! {
+    test_main();
+    loop {}
+}
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    test_panic_handler(info);
+}
+
+#[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);
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index b1d6211..22fb183 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,24 +1,32 @@
 #![no_std] // don't link the Rust standart library
 #![no_main] // disable all Rust-level entry points
+#![feature(custom_test_frameworks)]
+#![test_runner(amix::test_runner)]
+#![reexport_test_harness_main = "test_main"]
 
+use amix::println;
 use core::panic::PanicInfo;
 
-mod vga_buffer;
-
-#[unsafe(no_mangle)] // don't mangle the name of this function
+#[unsafe(no_mangle)]
 pub extern "C" fn _start() -> ! {
-    // this function is the entry point, since the linker looks for a function
-    // named `_start` by default
     println!("Welcome to Amix{}", "!");
-    panic!("ERROR!!!");
+
+    #[cfg(test)]
+    test_main();
 
     loop {}
 }
 
 // This function is called on panic.
+#[cfg(not(test))]
 #[panic_handler]
 fn panic(info: &PanicInfo) -> ! {
     println!("{}", info);
-
     loop {}
 }
+
+#[cfg(test)]
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    amix::test_panic_handler(info)
+}
diff --git a/src/serial.rs b/src/serial.rs
new file mode 100644
index 0000000..d0aa59b
--- /dev/null
+++ b/src/serial.rs
@@ -0,0 +1,37 @@
+use lazy_static::lazy_static;
+use spin::Mutex;
+use uart_16550::SerialPort;
+
+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)*));
+}
diff --git a/src/vga_buffer.rs b/src/vga_buffer.rs
index e2fee68..12392f1 100644
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -68,7 +68,7 @@ impl Writer {
                 let row = BUFFER_HEIGHT - 1;
                 let col = self.column_position;
 
-                let color_code = self.color_code;
+                //let color_code = self.color_code;
                 self.buffer.chars[row][col].write(ScreenChar {
                     ascii_character: byte,
                     color_code: self.color_code,
@@ -121,7 +121,7 @@ impl fmt::Write for Writer {
 lazy_static! {
     pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
         column_position: 0,
-        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        color_code: ColorCode::new(Color::White, Color::Black),
         buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
     });
 }
@@ -142,3 +142,25 @@ pub fn _print(args: fmt::Arguments) {
     use core::fmt::Write;
     WRITER.lock().write_fmt(args).unwrap();
 }
+
+#[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 = "Some test string that fits on a single line";
+    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_character), c);
+    }
+}