Modify the code to allow running tests on the host machine

Author: dylanmckay

src/main.rs

@@ -1,8 +1,17 @@
 #![no_std]
-#![no_main]
+#![cfg_attr(not(test), no_main)] // #![no_main] interfers with 'cargo test' when targeting the host machine.
 
 extern crate avr_std_stub;
 
 #[no_mangle]
+#[cfg(not(test))] // The main function interfers with 'cargo test' when targeting the host machine.
 fn main() {
 }
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn test_foo() {
+        assert_eq!(1, 1);
+    }
+}