Add more tests for println

src/vga_buffer.rs

@@ -168,3 +168,22 @@ lazy_static! {
 fn test_println_simple() {
     println!("Does this work?");
 }
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("Test many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    let s = "Test string that fits on a single line";
+    println!("{}", s);
+    for (i, c) in s.chars().enumerate() {
+        let screen_char_ptr =
+            &WRITER.lock().buffer.chars[BUFFER_HEIGHT - 2][i] as *const ScreenChar;
+        let screen_char = unsafe { core::ptr::read_volatile(screen_char_ptr) };
+        assert_eq!(char::from(screen_char.ascii_char), c);
+    }
+}